Installing Resonators into an X-pipe

[itoto]

Hi! I recently purchased a used bimmerworld x-pipe with the forward facing x-pipe and no resonators. Unfortunately there is a rasp sound I do not like, so I purchased some vibrant resonators. Where is the best place to put the resonators? I do not want to put it before the x-pipe so I don't disrupt the exhaust flow in any way before the "X." I was contemplating on putting it soon after the "X" because I thought it would prevent any travel of high frequency vibrations (rasp) further down the pipe, but I looked at bimmerworld's resonated version and they placed it all the way at the end for some reason. Any inputs would be nice, thanks.

[SYT_Shadow]

I'd put it after the X. Look at a stock xpipe and you'll see where there's space for resonators. You could probably put 3 per exhaust bank if you put them in place of the primary cats, secondary cats and resonators of the oem xpipe

[itoto]

Just an update!

I would like to say it was a success! I had the non-resonated BW x-pipe and it had a rasp whenever one applied decent throttle. This rasp usually began around 2k rpm.

Once I installed the Vibrant 1792 bottle resonators, I'd like to say most of the rasp is gone! I say most because I hear faint remnants of the rasp when I upshift around 2.5-3k. When I apply a medium-hard amount of throttle, the rasp is 99% gone. I can hear a really faint rasp but I have to be honing in and focusing on hearing the rasp, which no one does.

That being said, if someone has the resonated version and has the rasp, the rasp will probably be gone with another set of resonators.

I placed the resonators soon after the x on the x-pipe. I have no clue why BW put the resonators at the end. Video recording this weekend.

[pbonsalb]

I’d weld them.

[Vuu]

Originally Posted by pbonsalb

I’d weld them.

This, or use v-bands.

[Powashiftin]

Which mufflers? I have zero rasp with my Corsa mufflers.

[itoto]

@pbonsalb @Vuu: Thanks for the suggestion. Maybe in the future! I didn't weld because of fitment concerns and the thought of being able to adjust the tube length if necessary is appealing. I've been using lap-joint clamps, so far they seem to be holding the exhaust in.

@Powashiftin: Interesting! CNT mufflers, I love the loud and bassy tones.
I'm glad you don't have the rasp, but from looking online, I also hear the rasp from this guy's Corsa (Link: https://www.m3post.com/forums/showthread.php?t=1540486). If you want specifics, in the "Corsa cat-back exhaust in car," you can hear the rasp starting at 2:04-2:07 and 3:45-3:36. He speeds through the rasp rpm range so it is not exaggerated, but if one were to maintain that rpm and throttle, the rasp will persist. I'm sure there are other timestamps where this occurs. And if one thinks it's the heat shield vibrating, trust me, I tried to test/correct that before adding the resonators.
In addition, from looking online, the x-pipe also have rasp with Dinan. (Link: https://www.m3post.com/forums/showthread.php?t=1760861)

[Redd]

Originally Posted by itoto

but I looked at bimmerworld's resonated version and they placed it all the way at the end for some reason. Any inputs would be nice, thanks.

Probably to keep exhaust gas velocities high for performance. Putting a resonator closer to the engine will create more back pressure than placing it further downstream.

[itoto]

Originally Posted by Redd

Probably to keep exhaust gas velocities high for performance. Putting a resonator closer to the engine will create more back pressure than placing it further downstream.

Perhaps! When I think resonators though, I don't usually think of back-pressure because it's essentially straight tubing, but I guess the extra little volume that the resonators add along their length may contribute to some back-pressure. I'll gladly take the 1hp hit if there is backpressure :^>

[Powashiftin]

Originally Posted by itoto

@pbonsalb @Vuu: Thanks for the suggestion. Maybe in the future! I didn't weld because of fitment concerns and the thought of being able to adjust the tube length if necessary is appealing. I've been using lap-joint clamps, so far they seem to be holding the exhaust in.

@Powashiftin: Interesting! CNT mufflers, I love the loud and bassy tones.
I'm glad you don't have the rasp, but from looking online, I also hear the rasp from this guy's Corsa (Link: https://www.m3post.com/forums/showthread.php?t=1540486). If you want specifics, in the "Corsa cat-back exhaust in car," you can hear the rasp starting at 2:04-2:07 and 3:45-3:36. He speeds through the rasp rpm range so it is not exaggerated, but if one were to maintain that rpm and throttle, the rasp will persist. I'm sure there are other timestamps where this occurs. And if one thinks it's the heat shield vibrating, trust me, I tried to test/correct that before adding the resonators.
In addition, from looking online, the x-pipe also have rasp with Dinan. (Link: https://www.m3post.com/forums/showthread.php?t=1760861)

The mic between the mufflers really exaggerates the rasps. I get that "rasp" at that same RPM for a split second. I will say the DCT, in whatever setting/mode that video was in, shifted into that "rasp" RPM. I'm 6MT …

Whatever makes you happy !

[itoto]

pls excuse the wind noise on some parts, newb gopro user
timestamps are included in the vid
yes i use my blinkers