BMW M135i F20 Performance Parts & Tuning Mods

Top Brands For BMW M135i F20 Mods

For the turbocharged BMW M135i F20 you are spoilt for choice when it comes to aftermarket tuning. Below you will find a range of trusted performance brands supplying quality upgrades, from intake and exhaust parts to suspension, braking and styling mods.

BMW M135i F20 Exterior Styling Mods

Take the look of your BMW M135i F20 up a notch with exterior styling mods that really stand out, from body kits, splitters and rear diffusers to spoilers, custom grilles and other visual upgrades, you can sharpen the car’s lines and give it a more unique, aggressive road presence.

Handling & Suspension Upgrades

The BMW M135i F20 is quick out of the box, but the stock suspension is a bit soft and can feel floaty over bumps, with some safe understeer on the limit. Start with quality tyres and upgraded brake pads and fluid, this alone sharpens grip, braking feel and confidence on both fast road and occasional track days. Performance brake kits with larger discs and calipers help resist fade on repeated hard stops, giving more consistent pedal feel when you are really leaning on the car. Next, look at suspension tuning. Lowering springs or a matched damper and spring kit reduce roll and tidy up the ride height, while coilovers add proper adjustability for cornering balance and stance. Uprated anti roll bars, chassis braces and stiffer bushings tighten up the front end and rear stability, so the M135i feels more agile on turn in and more planted mid corner. Done in stages, these mods transform the way the car changes direction without ruining everyday comfort, making the F20 feel like the sharp hot hatch it should have been from the factory.

Frequently Asked Questions

What are the best first performance mods for a BMW M135i F20?

The usual starting point for the BMW M135i F20 is an ECU remap or tuning box, paired with a decent panel filter or intake and a cat back exhaust. This gives a noticeable bump in horsepower and torque without turning the car into a headache to drive every day.

From there, most owners look at an uprated intercooler, springs or coilovers, and better brake pads with performance fluid. These upgrades help the chassis and cooling keep up with the extra power so the car feels sharper, not just quicker in a straight line.

How much power can a tuned BMW M135i F20 realistically make on stock internals?

On the standard N55 engine and turbo, a well set up remap with breathing upgrades, such as intake, intercooler and high flow downpipe, can deliver strong, reliable gains over stock. Figures in the region of a healthy stage 2 tune are common, as long as the hardware and software are matched properly.

For anything beyond that level, such as hybrid or big turbo setups, you are into more serious builds and supporting mods. That means fuel system checks, clutch or gearbox considerations and regular, high quality servicing to keep things dependable.

Will tuning my BMW M135i F20 affect reliability?

Any performance tuning or ECU remap puts more load on the engine, turbo and drivetrain, so reliability depends on how sensible the tune is and how well the car is maintained. A conservative map with good supporting mods such as intercooler, fresh plugs and quality oil is usually very reliable for fast road use.

Issues tend to appear when cars are aggressively mapped on tired hardware or pushed hard without proper cooling and servicing. If you keep on top of oil changes, use decent fuel, warm the car up properly and stick to proven parts and software, the M135i can handle a solid level of performance upgrades.

What wheel and tyre sizes work best on a BMW M135i F20?

Most owners stick with 18 or 19 inch alloys for the BMW M135i F20. A common choice is an 18x8 or 18x8.5 rim with a 225 or 235 width tyre, which gives good grip, ride quality and keeps unsprung weight sensible. For 19s, 19x8 or 19x8.5 with 225 or 235 tyres is typical for a fast road setup.

Lowering springs or coilovers, offset and tyre profile all affect rubbing and clearance, so it is worth checking fitment guidance or asking us before you order wheels. Getting the right offset and tyre size means you avoid arch contact while still filling the arches for a more aggressive stance.

Do I need supporting mods for a stage 1 remap on my M135i F20?

A basic stage 1 ECU remap on a BMW M135i F20 usually works on totally stock hardware, assuming the engine and ignition components are in good health. Many owners still choose to fit a fresh set of spark plugs and use good quality oil and fuel before tuning, just to give the engine the best chance.

If you plan to drive the car hard or do regular track days, it is smart to budget for an uprated intercooler and brake upgrades. These are not essential for a mild map, but they help keep intake temps down and braking consistent, which protects the car and improves overall performance.

Is a decat or sports cat worth it on a BMW M135i F20?

A high flow sports cat or decat downpipe helps the turbo spool more freely and can unlock extra power when combined with a remap. On the M135i F20, this mod is often part of a typical stage 2 setup, paired with an uprated intercooler and intake.

Bear in mind that a decat will not be road legal for MOT emissions in the UK, while a quality sports cat keeps things much closer to legal and is usually the better choice for a fast road car. Either option will make the exhaust note louder, so factor that into your plans.

What suspension and brake mods are recommended for fast road or track use?

For fast road, a quality set of lowering springs or entry level coilovers, matched with uprated anti roll bars and good alignment, transforms the BMW M135i F20 without ruining comfort. This tightens body control and makes the car far more confidence inspiring on B roads.

On the braking side, performance pads, braided lines and high temperature brake fluid are a big improvement over stock, especially for spirited driving. For heavier track use, consider a big brake kit or at least larger discs and more aggressive pads, so your stopping power matches your engine tuning.

Final Thoughts On The BMW M135i F20

The BMW M135i F20 is a cracking all rounder from the factory, with strong turbo power, rear wheel drive balance and a cabin that still works as a proper daily. Its character is hot hatch meets baby M car, eager enough for a Sunday blast yet sensible for the commute. Stock, it already feels quick, but you can tell there is a lot of untapped potential in the engine, chassis and brakes. That is exactly where carefully chosen performance parts, tuning upgrades and styling mods come in. With a quality remap, intake, exhaust and intercooler, the N55 responds with noticeable gains while keeping things smooth and reliable when done properly. Heat management and plastic charge pipes are known weak points once you tune, so uprated coolers, alloy pipework and supporting hardware are popular and sensible mods. On the chassis side, the standard suspension can feel a bit soft and floaty when you really push on, and traction out of tight corners is not perfect. Uprated springs or coilovers, better dampers, anti roll bars and a sorted wheel, rim and tyre setup transform grip, body control and steering feel without ruining comfort if you choose well. Brakes and driveline are the other areas enthusiasts usually address on a tuned M135i F20. Performance pads, braided lines and better discs give more confidence on fast road or the odd track day, while a stronger clutch or gearbox software tweak can help handle extra torque. Put it all together and you end up with a BMW M135i F20 that feels sharper, faster and more engaging, yet still easy to live with every day. Whether you are chasing lap times, back road fun or just a cleaner stance with the right alloys and exterior upgrades, the platform is a brilliant base, ready for you to make it your own.