Assignment 5: Modifying E90-E93 BMW 335i With N54 Engine

Dear 335i drivers,

So, you see an M3 stopped beside you at a red light. Ahead of you is the perfect quarter mile. Next set of light shines green, traffic is clear. Your instincts tell you the M3 beside is ready to race and give you a run. What do you tell yourself? “Should I do it, or should I not?” Are you going to humiliate yourself from the extra 120hp under the M3’s hood? That’s the question.

After reading this post, your instincts will tell you M3s ain’t got shit on you. If you follow my recommendation, your 335i would be power on tap, yielding 400+ horsepower.  Think Corvettes or Lambos are fast? Well, think again after reading this blog.  

Don’t believe me? How about I give you a taste of it?


Full Bolt Ons

First things first, you will need all the necessary parts to help the car breath and dump exhaust faster and smoother.

  • Intake

Your car obviously comes with an intake, but stock intakes are usually very restrictive in terms of airflow and will decrease the potential power that your 335i can unleash.  The two reputable brands AFE and INJEN both make an intake for your engine.  Both designs consist of dual cone inserts, meaning they will have two filters, rather than one which comes stock.  This design yields 98% more airflow compared to the OEM one as claimed by AFE.  Pricing of both these intakes very similar and is up to personal preference and brand loyalty.  As a loyal fan of AFE, I choose the AFE intake due to its design in blue, setting off a contrast with the black engine bay.

  • Downpipe

The downpipe follows after the turbo component. Exhaust gas is dumped out from the turbo into this pipe.  As the downpipe gets more free flowing and wider, exhaust gases leave the system quicker, enabling the turbo to spin faster.  What do you get from a turbo that spins faster? POOWWAHHH!!  The the infamous turbo lag can be eliminated with a wider downpipe installation. On the market, there are many brands that make downpipes.  Again, brand loyalty and cost comes into play.  Reputable brands like Active Autowerks (which specializes in BMWs), Riss Racing, CP-E and AR Design all produce downpipes.  Out of these brands, Active and AR design have the most users through my observation on e90post.  If money is nothing to you, then Active would be my pick, mainly for it’s branding.  But if it weren’t the case, AR design sells a good quality stainless steel downpipe in both catted and catless form.  The difference between the two is catted would be more restrictive than Catless. But going catless might affect passing the SMOG test.  The choice is upon yourself, POOWWAAHH or SMOG test.

-Keep in mind the SMOG test is only required after 7 years old of the car in Ontario. (hint hint)

  • Exhaust

How can we forget an exhaust system?  Exhaust systems are mainly for sound aesthetics. Some cars gain quite a few more horsepower with a more free flowing exhaust but the exhaust that comes stock on the 335i has a good flow already.  The only downside to the stock exhaust is being too mute for my taste.  Again, cost, brand loyalty, fitment all comes to play with modding cars and in this situation, there is no exception.  Some people like to stick to the BMW Performance Exhaust made by BMW which retains factory warranty.  This exhaust provides a civilized tone that I like as a daily vehicle but can also growl when you step on it.  But please keep in mind; if you are going to go full bolt on, you should keep your worries for the warranty last because most of these mods would void your warranty.

Here are a couple of exhausts which like and won’t attract too much attention from cops.



-BORLA 335i

  • Computer/ ECU Tuning

This is where the car gets interesting.  With all the prior mods above, the car will not change drastically until you modify the ECU.  A broad description of the ECU is that it functions like the human brain.  This ECU controls almost every part of the car.  An example would be the ECU telling how much air the engine will need to breath and how much fuel should be mixed with the air.  With turbo cars in this case, the ECU will also control how fast the turbo should spin at each rev range.

I will not get too in depth with this matter because it is a very complicated, just like the human brain.  What I will explain is how the computer will make your car faster. After all, this IS the whole purpose.  After you install this computer chip, the electronics will alter the air fuel ratio to allow the turbo to spin faster and create more boost.  This boost is what gets the car running fast.  Lets quickly get to the facts; there are three main competitors in this segment.

These tuning companies all have the pros and cons and it is up to you to decide.


-Cheaper than Procede

-No wiring needed in the engine bay.

-Directly plugs into the port under the steering wheel for changing of the maps

-Different maps for different turbo boost pressure

-Small unit just like an Ipod to switch maps and clear engine fault codes


-Most expensive out of these three

-Need to do some wiring in the engine bay

-Auto Tune feature that the computer is smart enough to adapt to your car’s mods for maximum horsepower/torque

-Valet mode, allows the car to shut off the turbos so you can not only save gas but prevent valet parkers from destroying your racecar

-Launch Control

-Different maps for different turbo boost pressure

-Require a computer plugged into the car to clear codes


-Different maps for different turbo boost pressure

-Require a computer plugged into the car to clear codes

-Some complain about power surge in higher rpms

-Higher horsepower gains than COBB

-Need to do some wiring in the engine bay

So these are a few pros and cons of these computer flash which you can find more detailed information at:

Well, after all these mods, you should be in the 400+horsepower territory and is enough to take onto the M3.  Not only will you be hanging onto them side by side, you should be able to pull on them.

(Notice this is a 335xi meaning all wheel drive which will be slower due to weight differences)


After Full Bolt Ons~


335is’ have been on the market for quite some time.  Performance companies are pushing out turbo upgrades for some that need new turbos due to wear. Turbo upgrade would yield the highest amount of horsepower which is sufficient to give supercars a run for their money.

This company resided in the United States specializes in using the best materials to build bigger, stronger turbos for enthusiasts that want higher boost.  Although this turbo upgrade might cost a pretty penny, some say it is money well spent. This is mainly because many have already gotten used to the speed from the full bolt ons and in search for something quicker.

Here is an example of 335i vs Lamborghini Gallardo


“Ask any racer, any real racer. It doesn’t matter if you win by an inch or a mile; winning’s winning” 

Think so? What do you think of these mods? Give me a reply right below!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s