One of the most popular power modifications for the E9X M3 is some sort of primary cat delete. The E9X M3 X-Pipe is equipped with both primary cats (immediately after the header) and secondary cats (further downstream before the crossover). Obviously the primary cats are rather restrictive considering that it creates an incredible amount of back pressure immediately after the collector of the stunning S65B40 headers. This primary cat delete is analogous to the catless headers that many E46 M3 owners upgrade to.
Considering some of my complaints of the car, I knew that some sort of primary cat delete was something I needed. I contemplated test pipes, eBay X-Pipes, and a slew of big brand name X-Pipes. Ultimately, I decided to get one of the top tier stainless steel X-Pipes. In the end, I acquired a stunning X-Pipe designed by Evolve Automotive. What I really like about their X-Pipe is that it had high flow catalytic converters and a pair of resonators. This means very high flow, low back pressure, low rasp, and low volume when paired with my stock muffler.
Sound - Cold start sounds insane, loud, and wicked! Warm idle is much more subtle, but there is a slight growl and rumble. Light throttle exhibits no drone, low volume, low rasp, yet a clean growling tone. Overall, very classy and tasteful. Heavy throttle provides a very noticeable roar! It sounds like the V8 is now very awake. Rasp is still very absent, but pure ferocity is heard on a quieter scale considering the stock muffler.
Smell - I honestly do not notice any difference. This was a huge relief considering my experience with my E46 M3 when I went catless. Cold start, warm idle, cruising, windows up, windows down, literally little to none presence of olfactory nuisance.
Fitment - 100% perfection.
Power - Incredibly noticeable. Completely rid of all my complaints. Very strong low-mid-high end power. Upon my first 50 miles of driving, I felt that there was just more power everywhere! I honestly was not expecting to feel that much of a difference considering the weight of the car, but it is absolutely profound. At any point in the power band, you can mash the throttle and urgency will be present. I am only totally pleased and impressed by this very simple bolt-on modification. I wasn't sure what to expect when I finally got the chance to dyno. Upon analyzing the data, there is a very consistent 20-25whp gain all across the board! No wonder I felt such a big improvement in power regardless of state of the powerband.
2009 BMW E90 M3 DCT
DynoJet248X at Dean's Performance, St. Charles, IL
4th Gear | 220E | 93 Octane
Evolve Automotive X-Pipe w/ 200cpsi Cats
Evolve Automotive DCT Software
Notes: Consistent and realistic measurement was absolutely key with our data collection. To assure a proper controlled and accurate measurement, we assured to log several parameters to provide a level playing field. IATs were properly controlled and monitored for consistency. Ignition was logged so that the proper runs can be chosen where this does not become a variable, but a constant control. Please note how the ignition logs are identical between Stock and Evolve X-Pipe runs. To some degree, this strengthens the evidence of the sole effect of the X-Pipe and decreased back pressure. No dyno tricks, no misleading data, only candid and fair comparison. Notice how even the AFRs are nearly identical. Both of these logs prove that there is no tweaking of the DME, the MSS60 DME has stabilized for consistency, and most comparable runs were chosen.
SAE w/ Conditions
SAE w/ Ignition
Hardware transferred to Evolve Automotive X-Pipe
O2 Sensors transferred to Evolve Automotive X-Pipe
Recommended new hardware
I made the mistake of not analyzing the data on a closer more finite resolution, missing how there is a bit of a difference in Ignition logs between the posted stock and X-Pipe data.
So I went back through all my DRFs and chose Stock_RunFile_004 based of the Ignition I hit and how it was closest to EvolveXPipe_RunFile_006. Check out the comparison and data to help support why I chose these two specific runs. Even in this case, Stock_RunFile_004 still hit higher ignition targets, although I'm not sure to how much degree this could be advantageous or not. I looked over the data and made the following graphs. When choosing the most appropriate runs to compare to by using Ignition and IAT as a control, it seems like the following two runs might be more accurate.
I enjoy being candid with you all, so if anyone has any input and good information to educate us all, it would greatly be appreciated!
SAE - WHP vs AFR
SAE - WHP vs IAT
SAE - WHP vs IAT w/ Displayed Conditions
SAE - WHP vs Ignition
Circling back to my original dyno comparison at the beginning of this write up. Here is a closer look comparing the Ignition logs between Stock_RunFile_005 and EvolveXPipe_RunFile_006. Please note how the Stock_RunFile_005 hits a bit higher ignition compared to EvolveXPipe_RunFile_006.
Here's a graph depicting Stock_RunFile_004, Stock_RunFile_005, and EvolveXPipe_006. Notice between the two Stock_RunFiles how Ignition may potentially affect depicted power output, despite the minute difference in Ignition parameters.
And very lastly, he's a comical graph showing how easy it is to exaggerate gains by choosing the lowest measuring Stock_RunFile and highest measuring EvolveXPipe_RunFile. From my personal experience, the first few runs are usually low reading because fluids aren't up to temp, DME isn't hitting stabilized parameters, and the dyno rollers are still warming up. Pretty funny how it's so easy to "add" near 10whp delta in power by choosing misleading runs.