[Wellsybo]

Hello everyone,

I’m an interloper from the 1 series forum. I randomly purchased a 428i recently with no information and an extremely loud exhaust that gives a very low pitched sound and burbles a LOT.

I finally got under the car today to see what hardware was in place. I was hoping it was some high end race spec, turbo back straight through pipe to rear box. This was not the case.

The cat is in place and does not look gutted, but that doesn’t mean it is not.

From cat back the resonator is gone, no surprise there, but the entire horizontal rear box is gone too.

My first question is wether this configuration is a legit tuning method on these cars? Is it a ‘thing’?

My common sense thinks why weld and fit all that straight pipe and leave the cat in the there? Surely do the opposite and go turbo back, cat bypass, res delete and fit a high quality rear box?

My second question is would my car run without being mapped with this exhaust set up? I want to flash it with Bootmod3 but I’m unsure of the impact of the exhaust, if any??

Third and finally, if I were to buy a new system, what is the preferred / best configuration? I don’t want a crazy loud exhaust that makes people stare at me. I want a car that breathes well though.

Thoughts?

Thanks.

[rusty_sojah]

I recently got a 440i myself and am new to this platform having prev been in a 335is FBO n54 engine.

Sounds like it is just straight piped , or as close as you can get plug n play on this car. I've seen a few that remove the rear muffler 'box' and i assume it just makes it louder. I've seen a few of these while exhaust shopping recently and i think they usually seem a little cheaper but probably a little louder as well.

I have a valved setup stock so i am only looking for aftermarket ones that also have a valve in the rear muffler box so when i drive in comfort mode it is closed and wife friendly, but when i put it in sport mode it is much more tuner boy approved 👍

I also don't think bm3 would care either way. If it doesn't already have a tune on it that will probably make a nice improvment to the performance and sound as well. I just went bm3 stage 2 myself. Good luck/welcome and take some pics of the exhaust rear section next time if you can.

[Wellsybo]

Yes it turns out a res and muffler dekere is a thing. Not a very well advised thing!

I had a resonator fitted yesterday until i can find a rear box. Bootmod flashed it
today. Both have reduced some of the drone. So all good!

[Nachos23]

The reason you get no codes I suspect is because the Cat is in place and I suspect both pre and post cat O2 sensors are therefore present as well?

It's the post cat (secondary) O2 sensor the car reads to determine if the cats are working correctly... if it's there and not reporting a fault, the CAT is still intact. Having said that, there may already be a tune on it with CAT delete enabled, but doesn't sound like it.

Not sure why'd they'd go cat back straightpipe and leave Cat in place... but I do a ton of walnut blasting for this community here in Toronto and you'd be amazed the intake and exhaust setups I've seen... some crazy mods out there... LOL

Originally Posted by Wellsybo

Hello everyone,

I’m an interloper from the 1 series forum. I randomly purchased a 428i recently with no information and an extremely loud exhaust that gives a very low pitched sound and burbles a LOT.

I finally got under the car today to see what hardware was in place. I was hoping it was some high end race spec, turbo back straight through pipe to rear box. This was not the case.

The cat is in place and does not look gutted, but that doesn’t mean it is not.

From cat back the resonator is gone, no surprise there, but the entire horizontal rear box is gone too.

My first question is wether this configuration is a legit tuning method on these cars? Is it a ‘thing’?

My common sense thinks why weld and fit all that straight pipe and leave the cat in the there? Surely do the opposite and go turbo back, cat bypass, res delete and fit a high quality rear box?

My second question is would my car run without being mapped with this exhaust set up? I want to flash it with Bootmod3 but I’m unsure of the impact of the exhaust, if any??

Third and finally, if I were to buy a new system, what is the preferred / best configuration? I don’t want a crazy loud exhaust that makes people stare at me. I want a car that breathes well though.

Thoughts?

Thanks.