Absurd exhaust system proposal for e53 X5 3.0i M54 // headers back for under $1,250?

[IkirisTheX5]

Hi X'ers ,

I wanted to start this thread not only to satisfy my own goofy exhaust urges, but also to see what some of the more unconventional exhaust setups you guys have done to your own e53s or have witnessed others do to their's.

Following a litany of maintenance repairs, my X5 runs smoother and quieter than I ever remember her to have (or ever thought she could again), and for the first time since probably 2014 the CEL is off (80% of the time at least ). So after achieving this milestone and now quickly approaching 200K miles, I decided it would be a good time to fulfill a lifelong X5 ownership dream and f*¢# it all up by installing a completely new, silly exhaust system.

After reading numerous exhaust threads on here and other forums relating to the M54 engine, and taking inspiration from some YouTube videos of people with much higher end BMW's doing ridiculous things to their multi-thousand dollar, M-tuned systems, I've settled on the below design to satisfy my adolescent craving for a bad-ass sounding and hp boosting system that is economically sensible for an almost 20 year old car with nearly 200k miles on it.

What I'm hoping you guys can talk me out of is:

- anything that could harm the X5 in the long run,
- anything you think would impede performance rather than benefit it,
- anything I'm taking too lightly (or not considering the actual expense of) in terms of the ability of what a standard local muffler shop guy can do
- anything you see here that there is a better alternative for in the same ballpark expense wise

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From front to back:

- $120: Knockoff Supersprint Ebay headers for an E46 (I realize they are too short to bolt on to the existing tubing leading to the resonator, but since the whole system is being gutted I'm hoping it won't be too expensive for a shop to adapt e46 headers to an e53 chassis: $120 vs the next best thing, which are the $530 Russian Dr. Lavr e53 specific headers.)

- $20: (2) x 90 degree oxygen sensor adapter/extenders (I've heard that due to clearance issues on aftermarket headers the only way to fit the O2 sensors is with such an adapter... also a chance that this cat-less header setup w/ the extensions won't foul out the sensors and trigger the CEL)

- $20: (2) x 2.25" to 2.5" exhaust adapters (I understand stock 2.25 piping on the M54 3.0i, but since I'm gutting all I figured why not turn it up a notch to 2 1/2 inches all the way through... Why not just go all out for 3" in that case? The less exhaust restriction the better, right? Except for in case of torque I hear you want some back pressure, no?)

- $60: 10 ft of 2.5" exhaust tubing from headers/adapters to x-pipe and then x-pipe to mufflers

- $120: Magnaflow Tru-X X-pipe, 2.5" in/2.5" out (is there any advantage to the Magnaflow one or could I get away with a $40 Amazon x-pipe?)

- $80: (2) x Cherry Bomb M-80 mufflers (check out the guy on You Tube who put another type of Cherry Bombs on his late model M3 - I think it sounds great!: https://www.youtube.com/watch?v=wra6PEx6YiQ )

- $100: Knock off M3 style dual exhaust tips, 2.5" in/3.5" out X 4

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Thanks for humoring me if you've read this far. I just wanted to get some advice before ordering all this junk and finding a muffler guy willing to do it.

What do you guys think a shop would charge to do a job like this? I'm hoping I could strong arm a guy into doing the whole thing for under $600 labor if I supply all the hardware. Am I being unreasonable?

That would put the entire exhaust, header to tips, expense at under $1,250 ($520 parts + $600 labor + a little padding).

An Eisenmann sport cat-back exhaust would cost $2,300 in parts alone and doesn't include the headers which should provide the largest HP gain. Any reason to think that my proposed Frankenstein setup wouldn't yield the same performance benefits as an Eisenmann set-up?

***Can anyone recommend an exhaust guy willing to work on a cat-less setup in the North Texas/DFW area?*** (or should I just invest a few hundred more bucks in a set of universal high flow cats?)

attached are two diagrams I cobbled together: one of the stock exhaust system (apparently the internet doesn't have a diagram of the complete exhaust system solo for an e53 M54 X5), and one of my proposed silly exhaust system.