It's been too long since we last visited our 2012 F30 BMW 335i project. In fact, our last installment was in EC 4/13 when we compared our Mineral Grey car on its H&R Street Performance coilovers, 20" HRE C100 wheels and Nitto Invo tires to a similar car from LTMotorwerks. Our intention was to compare its suspension to the KW Variant 2 coilovers on the second 335i since we rarely see tests like that.

It was a fun exercise and, while we love the suppleness of the H&R components, the KWs did appear to provide slightly more control at high speed. You can read the full report in the 4/13 issue or online at

The ensuing delay can be attributed to the lack of available parts for the F30. But having waited for the aftermarket to get its act together, we decided to go with official BMW M Performance parts, available from any BMW dealership or online at

There's a comprehensive catalog of officially authorized performance and cosmetic components. These can either be financed and fitted on a new car, or added to an existing vehicle such as ours. There are parts for most models in the BMW range, so you don't have to own a 3 Series, but all the parts are OE quality, as you'd expect, and won't affect your factory warranty. When you visit the website it will display component prices and fitted prices, so you know what to expect.

We limited our cosmetic upgrades on our car to black kidney grilles and carbon mirror covers because we wanted to focus on the performance side. So we would also fit the engine Power Kit, big brakes and exhaust. This was fairly ambitious in our tight timeline, aiming to have the car ready for Bimmerfest and subsequently run the 335i against one of its competitors in the next issue.

To help us, we enlisted european auto source in Anaheim, CA for the mechanical parts, and to verify the improvements on their dyno. We'd also had the assistance of local BMW tech, Derek Vieira, who had worked on previous projects and was very familiar with the correct installation procedures. He would install the grilles, mirrors and engine hardware, while EAS worked on the brakes and exhaust before dynoing the Power Kit software.

Kidney Grilles

Fitting is relatively straightforward but you must be prepared to get stuck-in. The correct procedure would be to remove the front bumper but Derek found a shortcut...

Begin by undoing six T30 screws on the top edge of the bumper, under the rubber seal. There are also two T20 screws above the headlight housings.

Once removed, pull the top of the bumper away from the car and get your hand behind one of the grilles. Push the middle of each securing tab to release them. Work your way around the tabs to remove the grille. You'll need thin arms, long fingers and patience.

To fit the BMW M Performance black grilles, simply position and press until all the clips snap into place. You may need to apply some force. Then replace the screws in the top of the bumper and refit the rubber seal to finish.

Carbon Mirrors

Using a plastic blade and some force, lever behind the mirror glass to snap it out of its retaining clips. Then disconnect the heating wiring. The plastic mirror cover is held by three pinch clips, which should be released.

The new BMW M Performance carbon fiber covers are secured with supplied T10 screws and washers. To accommodate these, you need to bend or break the plastic tabs in the base plate for clearance.

Unlike the plastic covers, there's no ridge along the top edge to locate the carbon pieces, so the seal isn't as good. However, the screws seem to hold the new covers in place properly.

Finally, refit the glass by placing it over the center circle and wiggle it until the clips snap into place. It might be advisable to work with a cloth under the car in case the glass falls.


The BMW M Performance exhaust replaces the rear muffler on the 335i with a stainless steel part that has chromed 3" tailpipes (rather than the stock black tips on our Sport model) that are etched with the "M" logo. The muffler is fitted with the flap actuator to control backpressure, is supplied with full instructions (including a guide for where to cut) and comes with a large pipe clamp.

Arriving at european auto source, the first task was to mark the stock pipe for the saw cut. Measure carefully because you want the tailpipes to be in the correct place.

Once cut, disconnect the vacuum hose from the flap and undo two 13mm bolts on the hanger. The muffler can then be removed. The hanger should be transferred to the M Performance exhaust.

Before we fitted the new part we weighed both mufflers. The stock piece was 24.2 lb and the M Performance replacement was 21.3 lb, saving us almost 3 lb.

Having filed the sawn pipe smooth, slide the supplied clamp over the OE system and fit the end of the new muffler into the clamp. Then bolt the hanger back onto the car. Tighten the clamp once the tips are aligned in the bumper apertures. You then want to reconnect the flap.

This is a 20min DIY job, provided you have a lift and a good saw to get through the stock pipe.

Power Kit

As a relatively new addition for US cars, the BMW M Performance Power Kit in this instance consists of engine software, a new air box plus an M Performance engine cover that lets everybody know you have something sepcial.

Our car, being one of the very first 2012 models in the country, it couldn't be reprogrammed with a software flash, so a replacement ECU was supplied that would allow us to flash it. This makes our car more expensive but we're assured the results would be the same.

Installation of the hardware was straightforward. The stock engine cover sits on four columns, secured by rubber bungs. To remove, simply pull upwards. You'll need to exert some force but it will come off. Fitting the new engine cover simply required it to be pushed into place.

The replacement air box was another simple installation. Start by releasing the four metal clips around the air box lid. Then release the MAF sensor plug and unscrew the inlet hose clip from the other side of the engine bay. The plastic hose lifts off a rubber bung and is removed with the air box lid as one piece.

The base of the air box sits on another two bungs, so simply pull it upwards and away from the lower ducting.

The new base unit has an additional intake, outlined in orange. This will increase the air drawn into the intake and has increased induction noise slightly, as well as turbo whistle.

Push the new base unit onto the bungs, refit the filter element and the lid with new clips supplied. Then screw the inlet pipe back into position and reconnect the MAF.

For most owners, the installation will be complete. The car must then visit a BMW dealer to have the software flashed. It will require a software update as well as re-coding, so could take 3-5 hours. Our car required the ECU to be fitted, which was a more complicated job because of the ECU placement. It was then updated and flashed.

The overall flashing procedure is far slower than a software upgrade by aftermarket tuning companies, but BMW is re-coding and updating many functions on the car simultaneously, meaning this part isn't a DIY task.


Everybody likes a big brake kit and BMW offers its M Performance brake system with Brembo four-piston front and two-piston rear calipers. These require a minimum of 18" wheels and are available in red, yellow or orange. We selected yellow, which is reminiscent of the E46 M3 Phoenix Yellow, as it contrasted our grey paint nicely.

The rotor size is increased from 340mm front, 330mm rear to 370 and 345 respectively. They're also dimpled and grooved to aid pad performance. As a result, they make a slight thrumming sound when applied, which we like.

The kit is supplied with calipers, rotors, pads, heat shields, sensor wires, pad grease and nuts/bolts.

To install, undo the two 18mm front caliper bolts and release the pad sensor wire (it's only on the driver's side). Then hang the caliper safely out of the way. Undo the 6mm allen screw in the rotor and remove. You may need a rubber mallet to persuade the rotor off the hub. The hub should be cleaned and anti-seize solution liberally applied.

We opted to retain the stock heat shields since they were the same as supplied. So simply screw the new M Performance dimpled rotors into place and bolt on the yellow calipers. We used the supplied bolts for the latter, torqued to 60ft-lb.

Insert the pads (after applying more anti-seize to the backs) and secure with the supplied steel pins and spring clips. You can fit the new sensor wire at this point.

Leaving the messy job until last, use a 11mm open wrench to undo the brake line inside the fender well. You want to do this quickly to lessen fluid loss, reducing system bleeding. Brake fluid will strip paint, so clean any spills. The line then swaps over to the new caliper and screws into the fitting.

The procedure is exactly the same at the rear, but now the caliper is held by two 16mm bolts and the pad sensor is on the passenger's side. Re-torque the new caliper bolts to 60ft-lb again when refitting.

The final job, once the hardware is installed, is to bleed the brake fluid. european auto source uses an air pressurized shop system to make it easier, but consult an expert if you're unsure how to bleed brakes. Leaving air bubbles in the line can lead to a soft pedal or even a crash.

Equally important is to bed-in the pads before regular use. This matches the pads to the rotor face to ensure efficient operation.

There are several different techniques but we did it with repeated 60mph stops, allowing the brakes to cool before repeating. Ordinarily, this would give us a firm pedal and powerful stopping but we suspect BMW specified softer street pads that don't require the warm-up period of harder pads. So while they do stop efficiently, scoring well in MotorTrend's testing for its online video we'll discuss next month, the pedal feels a little numb. But that doesn't seem to detract from their overall ability, and they certainly look good, which also helps.


When the car arrived at european auto source we gave it an initial dyno run to record baseline numbers. The N55 3.0L turbo engine in the F30 335i is renowned for getting hot on the dyno, so EAS typically does several runs then allow it to cool down. Taking an average, our car recorded 261hp at the wheels and 299 lb-ft of torque. Not bad considering it's supposed to have 300 lb-ft at the crank!

After the BMW M Performance exhaust had been installed, we returned to the dyno and saw identical numbers. The guys at EAS explained that they'd run an F30 without a cat-back exhaust fitted and found no gains, so they weren't expecting much from the rear muffler.

On the plus side, the etched tailpipes look good, but ours sounded almost like stock. Obviously, you don't want a noisy exhaust, but you do want to hear how you spent your money. However, the M Performance muffler was very close to stock. So with no power increase and very little difference in noise, it comes down to a cosmetic consideration.

After visiting the local BMW dealer, we returned to the dyno to test our new M Performance Power Kit with its new air box and software. The car felt slightly more peppy on the road but it wasn't like the 335is cars, for example.

On the dyno we saw peak wheel figures of 276hp and 295 lb-ft. The power gains come after 4500rpm, with a useful spike from 5500-6500rpm, which means you have to work the car to feel the benefits. It also gets a torque increase at the same engine speed.

What makes a car feel fast is a boost in mid-range torque, which is evident from 4500rpm, but it loses torque from 3000-3500rpm, which disguises the benefits in the mid-range.

People who have driven later 335i models with the same software claim the cars feel faster than ours, meaning our ECU swap possibly didn't release the full benefits of the new software. So overall, for the cost of the exhaust and Power Kit, we have to conclude that the results were rather disappointing. But if you're looking for mods that won't affect your warranty, these are the best options available.

Part Supplier Price
Carbon fiber mirrors BMW M Performance $715 (pair)
Black kidney grilles BMW M Performance $143 (pair)
Exhaust BMW M Performance $1375
Brake kit BMW M Performance $2540 (front & rear)

Next Month We'll test our Project 335i against a modified Cadillac ATS

BMW M Performance
European Auto Source
4015 E. Leaverton Court
CA  92807
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