[colorado.e9x]

New exhaust thread time! Big credit to Raimund. He did a lot of R&D to optimize performance/sound. There's not a lot of documentation on custom exhausts on here so I wanted to share my adaptation of it.

This system is made entirely of 3" stainless steel starting with the merge collector.

Rai’s setup can be found here

Part List:
• 4x Exhaust Hangers $40
• 2x V-Band Clamps $130
• Catless Headers $360
• Y-Merge Collector $130
• Mandrel Bent Pipe $150
• Vibrant Resonator $110
• HKS Carbon Ti Muffler $380

[colorado.e9x]

Headers
HZ Racing (AA Replica)

https://www.bimmerpost.com/forums/sh...php?p=30163526

Check the above link for a full review. I've heard nothing but good things about these headers from users who ordered the correct ones.

I paid just under $360 shipped for these. Shipping time is like anything else from AliExpress, about 2-3 weeks. Really not a big deal at all considering the price. Upon arrival, everything looked great. Welds were well done. I had mine cerakoted along with my magnesium valve cover. I can't recall the price but it wasn't bad at all.

This is a good time to do some preventative maintenance, and replace O2 sensors.

[colorado.e9x]

Resonator
Vibrant 17950
(will edit soon)

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Muffler
HKS Carbon Ti Universal
(3" in, 4.75" out)

Initially I wasn't a fan of "fart cannons," but my best friend has really changed that for me. After selling his E90 a few years ago he's had an 07 WRX, 04 WRX STI, and mostly recently a 2014 EVO X. All of which had big JDM cannons. I'll be honest they all sounded great. His STI is what got my attention though. It had an HKS Carbon Ti on it. Carbon fiber wrapped shell, nearly 5" burnt tip, perfection. I've liked HKS since Midnight Club 3: DUB Edition, so it was really a no brainer for me to try it for myself. Besides these things were meant for JDM legends like the GTR and Supra, of course it'll sound good on a BMW I6.

[colorado.e9x]

Exhaust Pipe
•BLACKHORSE-RACING 3" Mandrel Bent SS Pipe
• Vibrant 10356 Merge Collector
• 2x Vibrant 1491 V-Band Clamps
• 4x .47" SS Exhaust Hangers

Mandrel Bent SS Pipe
The goal here is to keep the piping as straight and fluid as possible. Your average exhaust shop isn't going to be able to achieve this with steel pipe and a pipe bender. Traditional pipe is crushed/stretched. Mandrel bent pipe is the same shape/diameter throughout the bend.

Comparison


Y Merge
According to Rai's R&D, you have a couple options for merge placement.

"For the best sound, place the merge close to the headers. For more low end torque at the possible expense of more drone, place merge at the end of the transmission."

I opted for the latter to compensate for the N54 intake manifold.

V-Band
Purely for future convenience, these V-Bands will save me some time and a headache should I need a portion of the exhaust out of the way. One will be placed directly at the merge collector, the other somewhere between the muffler and resonator.

Hangers
If possible, I will use all OEM hangers for this setup. The .47" hangers I bought are the same size and style as OEM, and should slide into the original rubber just fine. Let's just hope they're long enough.

(will edit soon)

Picture credit to Rai

[colorado.e9x]

All Buttoned Up
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Sound Clips
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Rai's Setup