djdc78

finally decided to install a custom quad on the car earlier today. went with West's set up you can see on this topic:

https://5series.net/forums/topic/985...n/page__st__15

its actually a magnaflow encased x-pipe AFTER the stock resonators, to 2 round magnaflow mufflers, and out to quad tips.

for the most part, i love the tone and volume. surprised how deep it sounds and quiet it can be at the same time, but also how it gets significantly louder when WOT.

only problem is the dreaded drone/resonance in the 1500-2000 rpm range. what makes it even worse is that's usually my shifting point when accelerating from a stop. so it's a pretty loud drone all the way up to about 45 mph before it shifts up and the rpms drop from which it becomes surprisingly quiet. There isn't really any drone at constant highway speeds, which is pretty cool too.

now from searching the forums and some other research, it seems to be a recurrent theme with V8's. It's a 550i, sorry for not stating that earlier. Most of the threads were a bit older and so I was hoping somebody might be able to chime in on how I can make that drone a little bit more quiet. Of course I'm not expecting it to be quiet like my stock exhaust, but more bearable as the sound difference is pretty substantial in that range from any other range below 3K RPM's.

btw, when getting it installed, they first started by welding 2.5 piping from my stock resonators to the encased X-pipe. That's when I told them I wanted 2.25 piping for the system. They did go 2.25 the rest of the way. do you think if I had them change that front piping to 2.25 it would make a big difference? from what I understand, the drone is coming from the lack of exhaust pressure and smaller piping should get it to exit as opposed to bouncing in the muffler/resonators and reduce drone.

thanks for any info you guys might have, sorry it's such a long read.

dc