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Old 01-16-2012, 06:00 AM
I'm a DlCK! So what?
Location: Birmingham, AL, USA
Join Date: Sep 2011
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Mein Auto: E46 ZHP TS2+ Coupe
OFFICIAL: 330i/Ci Guide to Horsepower Gaining Mods (Sorted by Bang for the Buck)!

We see these threads each and every day, so why don't we put one thread at the top (like they look there anyway...) for a quick reference?

I've compiled a list of mods you can do for your 330i/Ci to maximize horsepower gains from best "bang for the buck" to worst. How did I come up with these figures? Simple.

HP $$$

Some of you may disagree with my order of things, but your input is always highly appreciated. I used a 330Ci/330i as the base vehicle for horsepower gains. Other models may be similar in gains, but not nearly as extreme as some. Also, keep in mind that by installing two separate items that claim 10 HP, you will not actually see a 20 HP increase, but more of a true 10 HP increase. Funny how that works, huh? If you look at this dyno chart (also featured in the Pulleys section), you'll see that with all the mods in place (plus a 3.46 differential and no performance software), the car only gained about 16 peak horsepower. Sadly, by installing all the basics and investing so much money and time into your car, it still isn't going to walk an ///M3. It will, however, probably make it a bit more fun to drive!

Before we get started, there is one VERY important thing we must cover:

This is by far the most important thing you can do before you start letting your automatic 323i crank out 780 WHP. Here are a few items that are guaranteed to need replacing:

As you may have noticed, I've added links to where you can purchase some of these items. Not every preventative maintenance item was covered, but I did try to tackle the most common ones.

Now you're probably jumping up and down in your sport seats, anxious to see the goods. Be careful not to cause any airbag lights, because that will be just another setback before you can afford these upgrades!


Yes... the "N Word". It's cheap, plentiful, can be used only when you want it, CAN BE safe (no guarantees!), but has a tank that always needs refilling. For the person on a budget, the Nitrous Express Proton Plus kit seems to be where it's at (from what I can gather). You get a variety of nozzles (35 HP, 50 HP, 75 HP, 100 HP, 125 HP and 150 HP), the bottle, and all other hardware along with a wide open throttle switch.

Since this kit is advertised on their website at just under $400, you can have horsepower for as little as $2.67 per horsepower (150 shot). Of course, running 150 shot of nitrous on a completely stock motor is NOT smart to do. They say the best rule of thumb for a 330Ci/330i is to run no more than a 50 shot, that way you don't get into timing, air-fuel ratios, etc. However, you can do what you want.

NITROUS BOTTOM LINE: $2.67 - $11.43 per HP.


We hear it all the time, "Headers are the best bang for the buck mod you can buy for horsepower!" This is entirely too true. A set of eBay headers can run you around $100 shipped to your door. $100 for a gain of nearly 15 HP sounds almost too good to be true. That's because it is. If you do not install the headers yourself, you'll be paying nearly $400+ to get them installed.

Now... if you opt for Active Autowerke headers, you'll be paying well over $1,200. That's SIGNIFICANTLY more expensive for a very identical item. Many of the new E46 owners I know are on a budget, so AA headers are out of the question.

ADDITION: Thanks to mvrk10256 on for some addition for this section...

Originally Posted by mvrk10256
  • Real world cost of eBay headers with DIY is about $250 (including gaskets, nuts, bolts, etc.).
  • It is an all day project, but it is not technically challenging.
  • None of the sims actually work correctly and will allow you to pass emissions.
  • LC1 is a wide band - nothing more nothing less. It has a narrow band output function, however it will read like a stock post-cat O2 sensor, so you will fail. does sell a programmable box (which actually mimics an O2 sensor, including the random purge test). Unfortunately, their customer service sucks and I have not known anyone who actually managed. But as far as I understand it is possible.

Also see my "Everything You Need to Know About eBay Headers" thread (click title for thread).
With the installation of performance headers, you will also have a significant change in exhaust tone and volume and you will also lose your catalytic converters. If you live in a state where they hook a hose up to your exhaust pipe to check emissions, these are not for you. With the use of a properly functioning O2 simulator, you can probably get by with an OBD II port check.

HEADERS BOTTOM LINE: $6.67 per HP to $80 per HP


This is a popular question with the younger "tuner" guys who get into BMW's with the impression it's a "German Honda". Sorry guys... BMW's are pretty sophisticated machines that are already well-tuned out of the factory. Why do you think it's so hard to get big gains from bolt on mods?

The most popular performance chip people seem to lean towards is the Conforti Shark Injector. I've read of gains from 7 HP all the way to 12 HP. Let's go with 10 HP for a good median for this writeup. It's very easy to use (plugs into the OBD II port) and is relatively safe. It raises your redline to a screaming 7,000 RPM (), removes the top speed limiter, improves throttle response, and so forth. It was programmed with the car with bolt on mods in mind (headers, intake, and exhaust).

Active Autowerke also has some performance software, but you have to send off your DME for a total reflash. Active Autowerke also has authorized dealers across the nation who can flash your DME, eliminating the need to be without a car for a few days. (You can find a list of their dealers here.) It's just a bit more expensive ($399 on their website), but they claim gains of 15 horsepower and 12 lb-ft. of torque, which actually makes this the better deal. On top of this, they actually flash your DME for YOU! If you have headers, they'll take note and program your DME to better accept them. By flashing your DME to suit your existing mods, you can actually see gains higher than what is originally expected. AA's software also raises the redline and removes the top speed limiter while improving throttle response as well.


NOTE: There is also the option of flashing the EU2 Software onto your DME yourself. Yes... a software flash DIY. This is the cheapest option to my knowledge (USB to OBDII cable and software for $36.00 and $7.00 shipping off, requiring a USB OBD diagnostic cable that runs from your laptop to your car. There are no solid numbers for performance increase, but claims of better idle, better throttle response, and a better torque curve have all been made (and many people will back up this claim). Definite numbers have not been proven, but people say they have noticed a difference. Please CLICK HERE for more information. You can find the cable mentioned HERE.


Long tube or short ram? Debates have gone on for ages about these, so do a little research before spending your hard earned money. Claimed gains can be anywhere from 3 HP (short ram) to 10 HP (long tube).

If you're the daring type, you could actually make your own cold air intake system for much, much cheaper than what you could buy it for. The air filter will be the most expensive part of your homemade intake.

Pricing varies tremendously on this mod, where it can range anywhere from $75 for a homemade one (filter included in that price) to $300 for a nice long-tube intake. For a happy medium, we're going to say intakes provide around 4 HP.

AIR INTAKE BOTTOM LINE: $18.75 - $75.00 per HP


I'm not getting into the debate on whether or not underdrive pulleys are going to screw up your motor, but they will free up some "lost" horsepower due to parasitic accessories such as power steering, the water pump, and the alternator. I had to go with the reasoning that these do not add horsepower... they simply free up power that was lost between the motor and the wheels. Average freed horsepower proven by the dyno has been "up to 11 HP". Now, that "up to" part is going to vary depending on your car. For all practical purposes, let's go with about a 5 HP gain (going off of this chart).

We have a variety of brands, but I'm going to stick with the top three trusted brands: UUC Motorwerks, Rogue Engineering, and Turner Motorsports. TMS comes in at the most expensive at around $277, UUC comes in at $199, while Rogue is priced at a competitive $185.



We all dream of hearing the supercharger whine or that signature "P'TSHHHH!" of a turbo's blow-off valve, don't we? There's only one problem: These systems are expensive, ranging anywhere from $4,500 to nearly $7,000! The gains will vary, depending on which motor you have in your car.

For this write-up, I will use the 3.0 liter M54. Horsepower gains will be anywhere from 140 to 180 HP for superchargers and 90 to 140 HP for turbo kits. Since each system has different gains, I'll break them down separately now.

Active Autowerke Stage 1 Supercharger Kit - 365 HP and 270 lb-ft torque; $4,400 - $31.43 per HP

Active Autowerke Stage 2 Supercharger Kit - 405 HP and 285 lb-ft torque; $5,995 - $33.31 per HP

ESS Tuning Stage 1 Supercharger Kit - 320 HP and 302 lb-ft torque; $5,350 - $56.32 per HP

ESS Tuning Stage 2 Supercharger Kit - 345 HP and 317 lb-ft torque; $6,850 - $57.08 per HP

Technique Tuning Stage 1 Turbo Kit - 315 HP and 305 lb-ft torque; $6,395 (manual transmission) - $71.06 per HP

Technique Tuning Stage 2 Turbo Kit - 375 HP and 370 lb-ft torque; $6,895 (manual transmission) - $45.97 per HP

Technique Tuning ZHP Turbo Kit - 325 HP and 300 lb-ft torque; $6,395 (manual transmission) - $71.06 per HP


A set of cams increases how high your motor can rev, allowing a wider, more usable power band while also increasing horsepower and torque figures. The gains (for the price) are minimal, but they are great if your intention is to maximize naturally aspirated power.

A good set of Schrick cams from Turner Motorsport will set you back around $1,175. A ZHP camshaft retrofit kit from ECS Tuning costs only $412. Expect gains to be in the 10 HP range.



We're not here to discuss which of these "sounds the best", but which is the best bang for the buck. Brand-name cat-back exhaust systems are going to be expensive. Tremendously expensive. You could always go to an exhaust shop and have them custom make you one, but you risk having shoddy work, minimal power gains, and (of course) a terrible exhaust note.

Cat-back exhaust systems can range anywhere from $750 to $1,500, each providing gains from 0 to 12 HP (assuming conditions are PERFECT). We'll go with a 5 HP gain along with a hell of a sweet sound.

EXHAUST BOTTOM LINE: $150.00 - $300.00 per HP (for engineered systems)

As you noticed, I did not include a differential swap in this guide. Reason being: It does not add or free up horsepower. It simply allows you to burn through your gears at a faster rate, letting torque and horsepower be more useable.

I hope you have gained some insight and some knowledge from this guide and hopefully it will answer questions many of you are probably going to ask anyway.

DISCLAIMER: All gains posted are advertised and reasonably expected with each upgrade. Real world gains could be more or could be less. A loss in power is also possible. Varying factors (such as wheel weight) have not been calculated in these claimed gains. By putting aftermarket parts on your car, you assume all responsibility and you know the possible risks associated with said parts. I am not held responsible for broken parts, losses of power, engine malfunction, wasted money, tickets written for emissions issues, and/or sad faces. You modify your car as you see fit. Everyone is unique. YOU ARE SPECIAL!

NOTE: This is a work in progress and I will try to update it regularly with information as it is received. If you see something that needs corrected, if you have a dyno chart, if you find other prices, shoot me a PM and I'll see the proper information gets added in the appropriate spots. Your participation is HIGHLY appreciated to help make this happen!

Last edited by SPDSKTR; 02-09-2012 at 01:49 PM.
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