Top 10 Best BMW 335i Performance Upgrades & Mods

The BMW 335i is one of the most popular sports sedans of the last decade, offering a great balance of luxury and performance. Packing 300 horsepower from its twin-turbo inline-6 engine, the 335i provides exhilarating speed right off the showroom floor. But any car enthusiast knows there’s always an opportunity to improve performance and driving dynamics.

So what are the best modifications and upgrades you can do to make your BMW 335i even faster and more fun to drive?

There are many directions you can take your modifications, from basic bolt-ons to complete engine builds. In this guide, we’ll cover the top 10 best upgrades and mods to increase BMW 335i horsepower, acceleration, handling, braking, and overall track performance. From easy ECU tunes to big brake kits and lightweight wheels, we’ll detail the most effective modifications to transform your 335i.

We’ll provide options at different price points and complexity levels, so whether you just want a quick DIY upgrade or aim for 400+ whp, you’ll learn how to customize your 335i to match your goals and budget. Time to boost your twin turbo inline-6!

ECU Tuning

One of the easiest places to start improving BMW 335i performance is by tuning the engine control unit (ECU). The stock BMW ECU comes pre-programmed conservatively to meet emissions regulations and ensure reliable operation. But this leaves quite a bit of untapped power, especially with the 335i’s twin turbocharged engine.

By flashing the ECU and uploading a custom performance tune file, you can gain significant horsepower and torque while also improving throttle response and turbo spool up. Popular ECU tuning brands for the BMW 335i include:

JB4 Performance Tuner – The JB4 is a piggyback module that plugs into specific ports underneath the hood to override the stock ECU signals. It’s one of the easiest and most affordable ECU upgrades. With the JB4, you can expect gains of 60-80 hp and 80-100 lb-ft of torque depending on supporting mods. The JB4 is also adjustable on the fly with Bluetooth and has built-in knock detection for engine protection.
MHD Flasher – This handheld flash tuning device works with iOS and Android to flash new tune files directly to the 335i’s stock ECU. Custom tunes tailored for your specific mods and fuel can safely provide 60-100+ hp gains. The MHD Flasher app also offers DCT transmission tunes, custom idle speeds, launch control, and digital gauges.
Bootmod3 – The Bootmod3 tuning device similarly allows you to flash new map files to unlock power. It has various stages to match your modification level. Custom tunes can be ordered from recommended tuners. Bootmod3 also provides DCT tuning, RPM limit adjustments, and more.
BMS JB4 with Flash Tuning – For maximum gains, combine the JB4 piggyback module with BMS’ own ECU flash tuning service. With race fuel and upgraded turbos, some users have pushed over 500 wheel hp using this combo on modified engines.

Professional ECU tuning caters the performance maps to your specific car and modifications to maximize power gains while maintaining reliability. On a stock 335i, expect +60 to 80 hp from an ECU tune alone.

Cold Air Intake

Adding a cold air intake (CAI) kit is a popular first upgrade for any turbo BMW. A cold air intake replaces the stock restrictive intake tube with a larger diameter pipe that draws in cooler outside air. Popular options include:

AFE BMW 335i Intake – This sealed system uses a Pro Dry S air filter and turboshield hydro shield to shield the conical filter from engine heat while preventing water ingestion. The tube smooths out the air path while the 6061 aluminum construction looks great in the engine bay.
VRSF Intake – With a curved intake pipe design, VRSF intakes come in silver or black powder coated aluminum. The kit includes a sealed MAF housing and custom silicone couplers. An integrated air scoop helps feed cooler air.
AEM Brute Force Intake – Featuring a durable and rugged roto-molded polyethylene airbox, this CAI withstands underhood temperatures. The oversized AEM Dryflow air filter provides excellent filtration and airflow.

Benefits of upgrading to a cold air intake include:

Increased Airflow – Larger intake piping and air filter surface area reduce restrictive intake bottlenecks. This allows more air into the twin turbochargers for boosted power gains. Expect +10 to 15 hp.
Cooler Inlet Temps – Isolating the air filter from engine bay heat soak results in a denser air charge for better combustion and less power loss. Some BMW 335i intakes even include hydro shields.
Faster Spool Up – Lower intake air temps and turbulence mean the 335i’s turbos can reach peak boost faster off idle for improved throttle response. Better low end torque makes the car feel significantly quicker.
Engine Sound – Less intake muffling means you’ll hear more of the twin turbo’s throaty induction sound for free!

Overall, a cold air intake is one of the best bang for buck mods to start improving your BMW 335i’s powerband. It’s also one of the easiest DIY bolt-on upgrades you can tackle in an afternoon with minimal tools.

Catless Downpipe

Another way to unlock the 335i turbocharged engine’s potential is by upgrading the restrictive stock downpipe and catalytic converter section of the exhaust.

The downpipe connects directly to the exhaust manifold turbo outlets, so removing bottlenecks here enables exhaust gases to escape easier. Popular catless downpipe options include:

VRSF Catless Downpipe – Made from T304 stainless steel with laser cut flanges, this 3.5″ downpipe maximizes exhaust flow. It has high quality v-band clamps and deletes the stock catalyst. Available with black or silver coating.
TMS Catless Downpipe – Also 3.5″ in diameter, the TMS downpipe uses slip fit joints and includes a flex section to allow for engine movement and prevent leaks. Offers smooth exhaust gas flow.
ESS Tuning Race Downpipe – For max gains, this 3.8″ diameter downpipe steps up the size while eliminating the cat. Made from quality stainless and includes all hardware needed for install.

Removing the catalyst and improving exhaust flow offers several benefits:

15-25 HP Gains – The reduced backpressure allows the turbos to spool faster while also improving top end power. The ECU will also adapt to the freer flowing exhaust.
Throttle Response – Catless downpipes reduce turbo lag off idle for much sharper throttle response. Performance feels significantly improved where it matters for driving.
Lightweight – Deleting the catalytic converter sheds quite a bit of weight from the exhaust system, helping acceleration and handling.
Sound – Expect a deeper and louder exhaust tone for more turbo spooling and blow off valve action.

Just keep in mind catless downpipes are not legal for street use in many areas due to emissions laws. As an alternative, high flow catted downpipes like from Active Autowerke flow better while still reducing emissions for street legality. A proper tune will be required to prevent any check engine lights.

Intercooler Upgrade

The stock intercooler is another common bottleneck in the 335i’s turbocharged induction system. Intercoolers work to cool the hot compressed air from the turbos before it enters the intake manifold and cylinders for combustion. Cooler intake air is denser and allows more oxygen for bigger power.

Upgrading to an aftermarket larger intercooler provides cooler charge temperatures and prevents heat soak during hard driving. Some popular options are:

Forge Motorsport FMIC – Made from high quality aluminium with cast end tanks, this huge front mount intercooler significantly drops intake temps. Larger cores give it more cooling capacity. Includes silicone hoses and clamps.
CXRacing Intercooler – Boasts an extremely thick core and end tanks to manage heat, even at high boost levels. At 29x9x3.5″, it has massive size to prevent heat soak. Great value forged aluminium upgrade.
VRSF Intercooler – This affordably priced 28x9x2.75″ FMIC has a bar-and-plate style core for efficient air transfer and cooling. VRSF has a few different sized options depending on your power goals.

Benefits of adding an upgraded intercooler include:

Cooler Intake Temps – Lower intercooler outlet temps promote cooler, denser air into the engine for better power delivery, especially during hard driving.
Prevents Heat Soak – The larger cores and end tanks retain cold temps even after repeated hard runs. Heat soak robs power.
Supporting Mods – A larger intercooler supports mods like downpipes, intakes, and ECU tunes by matching their increased airflow. Prevents becoming the new bottleneck.
Reliability – Cooler charge air temps reduce engine stress, which improves reliability when upgrading turbocharged performance.

While most intercooler upgrades are direct fit, some modifications may be needed to fit the piping depending on model year. Proper tuning is also key to maximize the benefits. Overall, a larger intercooler is critical for big turbo builds and pushing 400+ whp.

Nitrous Oxide Injection

For straight line and drag strip performance, one of the most effective mods is adding nitrous oxide injection. When properly setup and tuned, nitrous allows you to safely spray an extra 75-150+ horsepower on demand for incredible acceleration.

Nitrous works by injecting a mixture of nitrous oxide gas and additional fuel into the engine. Under the heat and pressure of combustion, the nitrous oxide breaks down and releases extra oxygen. This allows more fuel to be burned, producing a huge power gain.

Some popular nitrous kit options for the BMW 335i include:

ZEX Wet Nitrous Kit – A leading brand in the industry, ZEX makes high quality complete kits. Their stage 1 option offers 75 extra horsepower with everything you need. Fully adjustable from the cockpit.
Nitrous Express NX Bottle Heater – Colder outside temps can negatively affect nitrous cylinder pressure. The heater warms them up for optimal performance in all conditions. A must for wet kits.
Giggle Gas 50hp Tuner Kit – For mild power gains, this tunable wet nitrous system provides up to 50 extra horsepower. The progressive controller allows fine tuning of the power delivery.
NOS Mini 2-Stage System – This kit from NOS boosts power up to 150hp with staging. It heats and regulates the nitrous bottle pressure for precision control. The compact design fits easily in the trunk.

Nitrous benefits include:

Huge Power Gains – 75-150+ extra horsepower allows you to push the performance envelope and achieve quicker drag strip times. Great for road course passing too.
On Demand – Instant power delivery when you need it at the push of a button. Especially beneficial for highway roll races.
Tunable – Wet nitrous kits allow fine tuning fuel and nitrous injection for tailoring safe power delivery. Start small and work up.
Reversible – Completely reversible modification. When not in use, the 335i performs stock without any side effects. Easy HP!

Nitrous is best saved for dedicated track and drag cars due to the stresses it puts on the engine. Proper tuning and fuel delivery components are crucial for reliability. Start with smaller kits around 50-75hp and progressively work up to build motor strength. But used correctly, it’s hard to beat nitrous for instantly adding big power.

Lowering Springs and Coilovers

One of the first places to start dialing in BMW 335i handling is by installing lowered suspension. Lowering the center of gravity of the car inherently improves handling performance by reducing body roll and weight transfer.

Some top options for lowering the 335i suspension include:

Eibach Pro-Kit Lowering Springs – This popular spring kit drops the 335i roughly 1.2″ front and 1.5″ rear for better stance and performance. The progressive rate springs offer increased damping force for a comfortable ride.
H&R Sport Springs – H&R’s street performance springs lower the car 1.2″ front and rear. Engineered for improved turn-in with less body roll. Made in Germany.
KW V3 Coilovers – For independently adjustable dampening and ride height, KW coilovers are some of the best. They offer adjustable compression and rebound paired with ride height adjustment.
BC Racing BR Series Coilovers – If you want maximum suspension adjustability on a budget, the BC Racing coilovers allow customizing ride height, shock stiffness, camber, and more.

Benefits of lowered suspension include:

Lower Center of Gravity – Dropping the car’s center of gravity curbs body roll and weight transfer for flatter, harder cornering and better handling dynamics.
Improved Responsiveness – Less body movement means quicker weight transfer and reaction to steering and chassis inputs. Enhanced turn-in, transitions, and agility.
Comfort – Many lowering kits offer dampening designed for street comfort while still reducing rollover in turns. Coilovers allow adjusting stiffness.
Appearance – Lowered cars simply look better aesthetically with a more planted, performance-oriented stance.

The extent of lowering depends on factors like wheel and tire fitment. Many opt for a 1-2″ drop to improve handling performance while still allowing all-season daily drivability. Coilovers give the ultimate adjustability, but quality springs often provide a nice blend of performance and ride comfort for daily use.

Sway Bars and Chassis Braces

Complementing your lowered suspension, stiffer sway bars and chassis bracing mods take handling performance to another level by reducing uncontrolled chassis and suspension movement.

Sway bars, also known as anti-roll bars, resist body roll and keep the chassis flatter during cornering. Upgraded front and rear sway bars come with bushings and are direct replacements. Chassis braces tie suspension points together for a stiffer structure.

H&R 28mm Sway Bars – A popular upgrade, these thicker hollow H&R front and rear sway bars significantly reduce body roll and improve turn-in precision. An easy DIY upgrade.
Rogue Engineering Rear Shock Tower Brace – Adding a rear shock tower brace joins the towers together for less flex and better structural rigidity during hard driving maneuvers. Sharpens rear end responsiveness.
Turner Motorsport Subframe Reinforcement Kit – Weld-in gussets strengthen the front subframe area that is prone to flexing under hard loads. Maintains alignment better while improving steering feel and turn-in.

Benefits of stiffening the chassis include:

Reduce Body Roll – Thicker sway bars resist lateral suspension movement keeping the chassis flatter for more controlled cornering. Less body lean allows harder driving.
Better Suspension Geometry – Limiting chassis flex keeps suspension alignment closer to designed specs for more precise handling and sharper turn-in.
More Responsive Steering – A stiffer chassis allows steering inputs to instantly translate to the wheels without flex delaying reactions. Enhanced feel and control.
Higher Handling Threshold – Decreased chassis flex equates to increased grip and tighter handling. You can drive the car harder and faster into turns with more confidence and control.

Don’t expect sway bars and chassis braces alone to transform the car. But when paired with proper suspension and alignment setups, they take handling precision to the next level and allow much higher performance thresholds before losing grip. The combination yields greater overall handling capability.

Lightweight Wheels

By far one of the best bang-for-buck upgrades for acceleration, handling, and braking performance are lightweight wheels. Reducing unsprung rotational mass with lightweight wheels results in less inertia allowing the wheels to react quicker.

Some top lightweight wheel models that work great for the BMW 335i include:

BBS CI-R Wheels – Excellent lightweight forged BBS wheels that weigh around 19 lbs per wheel in 19″ sizes. Combine low weight with BBS’s quality German engineering and styling.
Apex EC-7 Wheels – Well priced cast flow-formed wheels that weigh as little as 16.5 lbs each in 19″ fitments. Lighter than similar designs costing much more.
VMR V810 Wheels – VMR’s V810 model strikes a nice balance by weighing around 23 lbs per wheel in 19″ while being very affordable. Made in various finishes.
Forgeline GA3R Wheels – For max performance, Forgeline’s lightweight fully forged monoblock wheels weigh only 17 lbs, but come at an ultra premium price.

Benefits of lightweight wheels include:

Faster Acceleration – Lightweight wheels reduce rotational mass, helping them spin up quicker for better initial bite, quicker spool ups, and faster acceleration runs.
Improved Handling – Less rotating and unsprung weight means the suspension can react faster to inputs and changes of direction. Reduces unwanted inertia.
Better Braking – Lightweight wheels require less force and energy to slow down and stop. Braking performance and distance is improved.
Ride Quality – Lighter wheels put less strain on suspension components allowing them to react properly. Smaller wheels with more sidewall provide a smoother ride.

On average, reducing each wheel’s weight by about 5-8 lbs results in noticeable performance benefit. Flow formed and forged wheels offer the best strength-to-weight but come at a higher price. Every pound shed pays big handling dividends.

Big Brake Kit Upgrade

Slowing down all that twin turbo inline-6 performance requires serious brakes. Upgrading the 335i’s braking system provides stronger clamping force, better heat dissipation, resistance to brake fade, and improved pedal feel.

Popular big brake kits for the BMW 335i include:

Brembo GT Brake Kit – The Brembo GT system features lightweight 2-piece floating rotors paired with Brembo’s excellent 6-piston front calipers for supreme stopping power. Kits include pads and all hardware.
StopTech ST40 Big Brake Kit – StopTech is another leader in braking systems. Their ST40 335i kit uses lightweight curved vane rotors with 4-piston ST40 calipers to improve braking performance for track or street use.
ECS Tuning Brake Kit – A more affordable big brake option, the ECS Tuning kit upgrades to 13.7″ front rotors with 4-piston calipers and slotted rear rotors. Includes all pads, lines, and hardware.
Power Stop Z23 Kit – For budget-minded enthusiasts, the Power Stop Z23 kit significantly boosts braking over stock using Z23 Tru-Cast rotors paired with multi-piston calipers and performance pads.

Benefits of big brake kits:

Stronger Clamping Force – Multi-piston calipers and larger rotors provide significantly more stopping force and resistance to brake fade during repeated hard stops.
Cooling Capacity – Slotted, drilled, and dimpled rotors disperse heat better. Larger sizes and 2-piece rotors also stay cooler. Prevents overheating.
Precision Control – Rigid calipers and rotors provide more precise brake pedal feel and modulation of stopping power. Easier to fine tune braking at the limit.
Lightweight – Many kits use 2-piece iron and aluminum rotors or curved vane rotors to reduce overall mass while retaining durability. Unsprung weight improves handling.

For street driving, some common brake upgrades like performance pads and slotted rotors can work well. But for dedicated track and performance use, a big brake kit is worth the investment for the massive boost in stopping power and endurance it provides.

Michelin Pilot Sport 4S Tires

The last piece of the performance puzzle is fitting ultra high performance tires like the Michelin Pilot Sport 4S. Sticky summer tires provide a night and day improvement in grip and traction over all-seasons or even max performance all-seasons.

Some benefits of upgrading to summer performance tires like the Pilot Sport 4S include:

Maximum Grip – Compounds engineered for warm, dry conditions provide extremely responsive turn-in and the highest possible cornering grip and limits before losing traction.
Lightning Quick Response – Performance summer tires react immediately to steering and suspension inputs for reflex-quick cornering and handling capabilities.
Precise Feedback – You can accurately feel how much grip is left through the steering wheel to push handling to the limit while still maintaining control.
Wet Weather Ability – Modern max performance summer tires even offer good wet grip with tread patterns and compounds that dispel water effectively. Much improved over older summer tires.

While all-season tires offer convenience, summer performance tires unlock a whole new level of acceleration, braking, cornering grip, and responsiveness. They allow much harder driving up to the limits of the chassis and suspension. The difference is truly staggering. Combined with other handling mods, they fully realize the car’s potential.

Conclusion

The BMW 335i responds extremely well to modifications and upgrades. With the right combinations, you can extract a lot more horsepower and dramatically improve handling dynamics to create an even better performing sports sedan.

We covered some of the most effective power adders and handling mods like ECU tunes, intakes, sway bars, brake kits, and tires. But the possibilities are nearly endless for customizing your 335i.

Just take things in stages, starting with basic bolt-ons and suspension tweaks. Then move up to more advanced mods like superchargers, turbo upgrades, or even a full engine build to create a monster 400hp+ 335i. The aftermarket support and upgrade paths for the platform are plentiful.

With care and smart modding focused on your goals, the potent twin turbo inline-6 can be unleashed to much greater potential. A modified and upgraded BMW 335i truly comes alive and transforms into a world class sports sedan that’s even more enjoyable to drive on road and track.