E46 M3 Headers

One of the best mods for the E46 M3 S54 engine are headers and it’s hard to argue it. Not only does it bring out an aggressive tone in the sound department, but it also has one of the best horsepower per dollar figures. I put together an E46 M3 Header Guide article a few years back that compiles some of the more popular header options in the market and I’ve always been curious about power results among the brands. Does it really make a difference? Luckily, I have lots of data of my runs on the same dyno at European Auto Source so whatever I test, I’ll have data to compare against a lot of different setups. And guess what? Recently I just got some ARH E46 M3 headers.

Do stepped headers make more power? Does the Supersprint enlarged diameter really produce the most horsepower? There’s a header not on that list because at the time I wrote it, the product didn’t exist. Welcome the American Racing Headers (ARH), the first 6 into 1 mass produced header, to the picture.

ARH Background

Who or what is American Racing Headers? They’re an American brand (you guessed right) that takes a lot of pride in making high performance, quality exhaust systems right here in the USA – 100% of it. They focus mostly on domestic vehicles, but offer a small line of products for foreign OEM’s like Lexus and BMW. Out of nowhere, they started producing special ARH E46 M3 headers which is 6 into 1 long tube header design for the S54. It consists of six individual 1.75″ primaries mating to one 3.5″ section 1 all made in T304 stainless steel with .049 wall. What does that do? The idea is that unlike the traditional 2-piece header, a 6 into 1 with their “patented rotational firing” design will optimize airflow (even more than the traditional headers) to produce significant power on the S54.

Oh yeah and also, sound! The design of the 6 into 1 should alter the sound ever so slightly, but in a way that it replicates the sound of a V8. We’ve all seen that mysterious video uploaded on YouTube in 2007 titled “Custom M3 Headers” right? I think it’s still a mystery to what exhaust setup it is, but apparently it is a 6 into 1 like the ARH.

Horsepower Claims

ARH E46 M3 Headers Test Results

Okay let’s move onto some numbers. American Racing Headers conducted their own tests comparing a stock E46 M3 S54, traditional header setup and ARH header setup. Both header setups include an intake and tune. They published the following results:

  • 65 whp gain vs stock
  • 15 whp gain vs 'traditional' header
  • Dyno graph shows linear horsepower and torque gains without any significant dips, especially in the low end RPM range

So when you put the data in a table, it looks something like this below. Delta (Δ) is comparing against stock run file.

SetupWHPΔ (WHP)WTQΔ (WTQ)
Stock~270-N/A-
Traditional Header320.0050.00246.60N/A
ARH Header335.3065.30248.40N/A

Community Results

I know going into this ARH setup, I knew I was going to most likely see a dip in torque – especially the low end of the RPM range. I knew this because I talked to 2 other owners and did a bunch of digging to set expectations before I pulled the trigger on the ARH. All the users I talked to and all the research I found led to strong signs of torque loss, but I still pulled through because…well I’ll tell you why exactly at the bottom of the read.

ARH E46 M3 Headers Dyno Results

Tuned ARH Results

Onto my own results. I’m running the ARH headers, Bimmerworld ‘street/track’ section 2 mated to a Bimmerworld Race 3.5″ section 3. Supporting engine mods include a Turner Motorsport CSL Airbox and Kassel Performance MAP sensor all controlled by the MSS54HP ECU with a HTE custom dyno tune. Unfortunately no off-the-shelf tune will work with this setup and Hassan has a lot of experience tuning these headers so I chose him to tune this beast. Results below:

  • Red line = baseline run (no tune) on 91 octane
  • Blue line = tuned on 91 octane
  • Green line = tuned on E30 ethanol blend (APE Flex Fuel kit)

Summary

  • 64.31 whp / 15.17 wtq against stock running 91 octane
  • 68.25 whp / 17.66 wtq against stock running E30 blend

So in terms of max power, it did great! It was actually on par with the ARH claim of 65 whp over stock as I made 64 whp over stock on 91 octane. I also made more than my previous Evosport ‘traditional’ header setup so all good right? Can’t answer that yet until we look a little further. Max horsepower is just a vanity number. What you really need to see is the dyno graph and how much of that power is sustained throughout the RPM range.

E46 M3 ARH Headers Dyno

Here are the max numbers in a table view. I also added in my stock tune run file with only exhaust and intake. No headers. Delta (Δ) is comparing against stock run file.

SetupWHPΔ (WHP)WTQΔ (WTQ)
Stock286.37-245.43-
ARH Baseline Run (91 octane)328.6242.25244.34-1.09
ARH Tuned Run (91 octane)350.6864.31260.6015.17
ARH Tuned Run (E30 ethanol)354.6268.25263.0917.66

Tuned ARH vs Evosport 'Traditional' Header Results

This section of the article is now supportive of what the community claims have been: torque loss. I overlaid my previous setup with Evosport ‘traditional’ headers and E30 ethanol. All the others supporting mods are the same e.g. CSL airbox, Bimmerworld race exhaust, E30 ethanol, etc.

  • Red line = American Racing headers
  • Blue line = Evosport ‘traditional’ headers

Summary

  • At 4k RPM we are seeing a ~34 wtq loss and ~26 whp loss with ARH
  • We are also seeing a significant drop in torque from 3.2k-5k RPMs with ARH
  • After 6.2k RPM we see a steady 1-6 whp gain and 1-4 wtq gain with ARH
  • 11.72 whp more than Evosport setup (ARH claim was 15 whp)
E46 M3 ARH vs Evosport Headers Dyno

Here are the max numbers in a table view. I also added in my stock tune run file with only exhaust and intake. No headers. Delta (Δ) is comparing against stock run file.

 WHPΔ (WHP)WTQΔ (WTQ)
Stock286.37-245.43-
ARH Headers (E30 ethanol)354.6268.25263.0917.66
Evosport Headers (E30 ethanol)342.9056.53264.8819.45

⚠️ Evosport run result is running OEM CSL tune from MSS54HP and the limiter has a hard cut at 8k RPM. A quick Excel predictive formula shows max whp at 344 whp and 221 wtq at 8.2k RPM. Both are less than the ARH results at 8.2k RPM.

You Said Torque Loss Doesn't Matter, Why?

The loss in torque isn’t a major concern for me because this is a track-only vehicle where it lives in the 5k+ RPM range on track. This is my use case. For yours, it might be different. If you’re just mostly street driving then you’ll definitely feel a difference in power down low if you’re coming from a traditional style header setup.

So back to my track use-case. According to the dyno results, I’ll see significant torque loss if I am below 5k RPM and even if I do dip down I don’t believe it will have significant impact on my lap times. For the areas of the track where I am dipping down to the low RPM range, I can also try shifting one gear higher to keep the car in higher power range. Also worth to note, I am running shorter 3.91 gears so naturally the car wants to be in a higher RPM range which helps.

I just recently took this ARH E46 M3 headers setup to the track to see real world results and the data shows I am mostly in the 5k+ RPM range. The car pulls hard up top and I do think it’s faster than the previous traditional setup. Sacrifice low end torque, that I’m rarely in, for high end horsepower. Even when driving mindlessly around the track there wasn’t a section where I felt down on torque. Actually didn’t come across my mind at all on track even during the 2 slowest parts of the track where I leave it in a lower gear normally. This thing pulls hard all the way to redline.

Overall Takeaways

At first when I saw the dyno results I had second thoughts about sending it back to EAS and telling them to put my old headers back on. But I had to give it a shot on track. Yes, the torque just disappears down low. Yes, even with a tune the low end torque is unrecoverable. However, after actually driving it on track I am very happy and will not go back. This ARH is here to stay.

Lastly, another reason why I am keeping it. The sound! I think it sounds so much better. I mean, part of modifying is not only just to go faster but a balance of form and function. You’re not going to get this type of sound with any other traditional header so that alone makes a car so much more unique. Take a listen for yourself below and if you have these headers, please share a link down below in the comments so I can hear other setups!

Pros

  • Lots of horsepower potential after 5k+ RPM, more than traditional style headers
  • Unique exhaust note throughout the entire RPM range
  • Mates to OEM style section 2 for bolt-on connection
  • Built with high quality T304 SS

Cons

  • Loss of torque below 5k RPM
  • Expensive
  • Tight clearance to install, may require hoisting engine in the air
  • Requires custom tune to restore as much torque as possible
Join Waitlist We will inform you when the product arrives in stock. Please leave your valid email address below.
%d bloggers like this: