[evo335xi]

My xdrive n55 with downpipe sounds great with ample power gains,especially running a tune with it. I would like it louder so I am searching for the best muffler setup to accompany the downpipe and am almost certain I'm going to add the BMW perf exhaust and leave my secondary cats.

The rasp that accompanies my car now during 1/2-3/4 throttle is annoying, like a boom from underneath the hood. At full throttle it sounds great with little rattle at any other point. The boom is annoying enough that I have contemplated removing the downpipe and may just add the mufflers,delete the secondaries, and add a front mount to cancel out the powerloss and avoid heat soak.

Is anyone else experiencing the boom? It is not drone because at steady throttle I don't mind the exhaust sound. Would you trade a downpipe for a fmic and am I missing something that can change my current sound issue?
Thank you in advance, let's see what you guys got!

[Shogun1122]

I'm cattless dp with no secondaries and I have never heard a boom. Rasp, definitely but no boom.

I'm a manual and on high rpm quick shifts Ill get a crack sound but not a boom.

[CPWINCH]

go with m performance. And replace the secondary cats with long resonators!

[evo335xi]

My booming resonance I guess you could say is very present around 2000-2500rpms with light load and half throttle.

I took a few clips but it is not audible in them at all oddly! The sound is only present at partial throttle driving around. In neutral there is nothing. It's very strange but was told it was from removing the cat in the downpipe?

Im just unsure if others have this and get used to it.

Anybody live near Brewster NY who wants to compare or hear haha?

[evo335xi]

Bump for any help/suggestions!

[mashimarho]

bmw performance exhaust

[evo335xi]

I know it sounds great on the n55, even with a downpipe. I'm concerned with the raspy boom/resonance that I have now.
I just need some clarification if it is common and I can move forward.

If I'm stuck with it..I'm considering removing the downpipe, adding the BMW performance exhaust with a drop in intercooler.

[rr006rbc]

What is this boom u speak of? I have a 6 speed manual with PE and an aR design catless downpipe and all I hear is roar and turbo spool..2013 N55. I have no interior cabin noises at all engine RPM's

[evo335xi]

Almost like there is a leak, raspy, engine note thats boomy but only around 1/2 throttle 2-3000 rpms and then it is throaty passed that.

I've had exhausts on every car I've ever owned, even a straight piped Evo 8 but never had a boomy resonance from a downpipe. Lets say I hear it from underneath me/the hood versus behind me from the tailpipes.

[hetzle]

Which DP are you running? I've never heard of a "booming" from the engine bay

[evo335xi]

Bms 3.5 downpipe. I'm not sure if the sound is common or not to be honest. I guess it could be rasp that disappears around 3000rpms but it is not apparent in neutral. The more load the car has, the worse it seems. 1/2 throttle is when it occurs most, engine warm or cold. Could it be vibrating against something? Before the car gets throaty, its like a loud buzzy resonance or boom not just coming from the tailpipes.

[hetzle]

Originally Posted by evo335xi

Bms 3.5 downpipe. I'm not sure if the sound is common or not to be honest. I guess it could be rasp that disappears around 3000rpms but it is not apparent in neutral. The more load the car has, the worse it seems. 1/2 throttle is when it occurs most, engine warm or cold. Could it be vibrating against something? Before the car gets throaty, its like a loud buzzy resonance or boom not just coming from the tailpipes.

Your best option for diagnosis is to record it

[Shogun1122]

It almost sounds like you are describing drone. Light load at a constant RPM.

Although i also have BMS cattless downpipes and have experienced almost no drone.

I would try and record it as well and post it here. Sometimes describing a sound can be difficult.

[evo335xi]

There is a hum cruising which would be considered drone holding a constant speed. I like it, lets you know you have an exhaust back there. This is in gear 2-3000rpms 1/2 throttle. I'm guessing it is buzzy rasp that goes away from doing a ton of reading. It's an annoying boom that people live with I guess?!

If there's anyone local who wants to hear or let me hear it'd be great..just to put this to rest finally haha.

[evo335xi]

UPDATE: Decided to add Corsa mufflers in place of the stockers. The buzzy resonance from the downpipe only has been toned down and the roar from the mufflers is rediculous. I will add clips to my downpipe only vid if you haven't seen.

Best sounding combo by far. Thanks Bryce ACIDYNAMIX!