Ultimate fix for Supersprint catless exhaust drone - Vibrant 1792 resonator

[deni2s]

On my m52b28 with s52 cams, simota CAI and alpina intake I switched from stock exhaust to Supersprint catless config: Race headers, large diameter 2,5" midpipe, sport (the quiet one, not race) muffler.

Two things made me worried - unexpected then by me unpleasant drone at 3000 rpm and exhaust sound level measured at MOT of 90dB (official limit to pass local MOT is 85dB, but they let me pass).

I was considering custom Helmholtz resonator, but the guy who makes them wasn't really sure it will help my situation. Then someone on this forum pointed me to Vibrant products. So I choose the smallest resonator they had for 2,5" pipe - 12"x4" 1792 (1791 is for regular 2,25" pipe) and found this thread with lot of great reviews on eliminating drone: https://www.e90post.com/forums/showthread.php?t=336138 . It sounded too good to be true, and the thread was about N54 engine, but I decided to investigate more...

I contacted Vibrant, they told me at first that they usually recommend to put cats back (that's the most common route), but after talking a bit more they said, that they can't guarantee, but they think the resonator might help in my situation. And pointed me to European distributor of Vibrant resonators btnperformance.com, where I bought the resonator.

Installed resonator just a couple days ago, and I can say that it really does the magic - the sound of exhaust is maybe just a bit quieter than before, but there is no drone at all at 3000 rpm (and overall). The exhaust still have that cool low sound I really like, but no unpleasant drone anymore at all! Another thing to point out is that resonator is not restricted at all - if you look inside, you can see through 2,5" hole without any restrictions and looks nicely made and it's just 62$. So highly recommended so far!

P.S. I will try to record and add some videos with sound later.

[Vintage42]

... was considering custom Helmholtz resonator... Then someone on this forum pointed me to Vibrant products. So I choose the smallest resonator they had...

Just to be clear, the straight through Vibrant resonators to not use the Helmholtz principle which uses a separate and tuned side cavity.
https://en.wikipedia.org/wiki/Helmholtz_resonance

[deni2s]

Some feedback 1000km later... Unfortunately some of the unwanted sound is back. According to Vibrant it's probably due to heat inside exhaust, which resonator can't stand. Probably I will look for their high flow cats for next season.

[ihm96]

Any updates? I have a magnaflow muffler recently installed and my resonator was already deleted so I’m considering either adding back the stock resonator or a vibrant. The car has a nice tone and rasp but drones a lot between 2500-3000

Some feedback 1000km later... Unfortunately some of the unwanted sound is back. According to Vibrant it's probably due to heat inside exhaust, which resonator can't stand. Probably I will look for their high flow cats for next season.

[raubritter]

I had a similar saga: custom exhaust from cats back with x-pipe, no resonator, then Billy Boat mufflers. Sound was insane at high RPMs... amazing wail that gave me chills. However, skull-splitting drone at low <2500 RPMs, especially under really low load. Horrible.... truly horrible.

So I got Magnaflow resonators added which toned everything down (including the amazing wail at high RPM) yet didn't completely get rid of the drone.. So I got Supersprint mufflers. Pretty good overall, but not the liquid beautiful sound that the car had stock... sort of rough. But now only a minor drone at really low, say 1800-2000 RPMs which I can avoid pretty well.

Anyway 'resonators' are actually de-resonators, and resonance=drone, so if you have drone the resonators should help (that's what they were there for originally). Knowing what I know now, I would have just replaced mufflers at the back. BMW did a great job engineering out drone from the stock setup.

I've learned with all my different exhausts that they all start off more silent, and get louder over time (whether this is good or not depends on you). Personally I've grown to hate loud exhausts, and would much rather hear the engine than the exhaust (on the 2009 Mini I have, they actually added a resonance chamber in the intake path that causes the intake to be louder inside the car. Sounds pretty mean for a 4-cylinder, and probably adds less noise to the outside world).

I looked a lot into reducing drone. Exhaust guy told me it's important to avoid long straight paths of pipe. Factory exhausts kink back and forth to reduce this.

My own thoughts:
- Keep resonator or add good ones.
- Consider keeping your stock exhaust. Drone's a b#@#$.

Some questions I never found solutions/answers to:

- BMW exhaust pipe at least toward the mufflers is double-walled steel. Could this reduce drone? Billy Boat mufflers have built in 'resonators' right before the main mufflers (for all the good that does). So maybe something can be done in that area.

- Helmholz- would love to see someone's solution to drone using this...

- Heavier gauge steel exhaust pipes? People like the 'light weight' of aftermarket systems, but maybe that heavy steel helps dampen drone...

- Header wrapping around pipes? I wonder if this could help?

- Stock muffler had a rubber damper thing attached to the front... I wonder if something could be done like that.

Anyway I'm ok with my setup now, but I miss the stock refinement.

[ihm96]

I like a nice sounding exhaust, but I don't like drone. On my E34 which is a V8 I had removed the factory system witha similar style to what I just did and it sounded exotic at high RPMs, wasnt droney at all and made me so happy. This one sounds awesome above 4k and has some nice deep crackles, but it blows my ears off with the windows down around town and I can actually hear the droney resonance echo when coasting on the highway with them down. I can feel headaches starting to come on almost and it makes me worried about long drives. Will try the vibrant and see what happens.

On this car I initially did a res delete two years ago as someone told me it would keep the sound nice and quiet but make it a little throatier which it did but wasnt enough. I had kept my resonator to put back on in case, but then it got thrown out I think when some spring cleaning happened. I would just put that back on but I don't have it. There is a used resonator off a 3.0 Z near me for 60, but the reviews on this vibrant resonator seem to fit my goal.

I wish Dinan still offered the exhaust for this car cause they do such a good job at making them sound good but keep it quiet at cruising and in the cabin. Worst case if I don't like the results with the Vibrant I'm gonna do some research on their E46 328i exhaust to see if it fits since its designed for the same M52tu I have and they still offer that exhaust.

I had a similar saga: custom exhaust from cats back with x-pipe, no resonator, then Billy Boat mufflers. Sound was insane at high RPMs... amazing wail that gave me chills. However, skull-splitting drone at low <2500 RPMs, especially under really low load. Horrible.... truly horrible.

So I got Magnaflow resonators added which toned everything down (including the amazing wail at high RPM) yet didn't completely get rid of the drone.. So I got Supersprint mufflers. Pretty good overall, but not the liquid beautiful sound that the car had stock... sort of rough. But now only a minor drone at really low, say 1800-2000 RPMs which I can avoid pretty well.

Anyway 'resonators' are actually de-resonators, and resonance=drone, so if you have drone the resonators should help (that's what they were there for originally). Knowing what I know now, I would have just replaced mufflers at the back. BMW did a great job engineering out drone from the stock setup.

I've learned with all my different exhausts that they all start off more silent, and get louder over time (whether this is good or not depends on you). Personally I've grown to hate loud exhausts, and would much rather hear the engine than the exhaust (on the 2009 Mini I have, they actually added a resonance chamber in the intake path that causes the intake to be louder inside the car. Sounds pretty mean for a 4-cylinder, and probably adds less noise to the outside world).

I looked a lot into reducing drone. Exhaust guy told me it's important to avoid long straight paths of pipe. Factory exhausts kink back and forth to reduce this.

My own thoughts:
- Keep resonator or add good ones.
- Consider keeping your stock exhaust. Drone's a b#@#$.

Some questions I never found solutions/answers to:

- BMW exhaust pipe at least toward the mufflers is double-walled steel. Could this reduce drone? Billy Boat mufflers have built in 'resonators' right before the main mufflers (for all the good that does). So maybe something can be done in that area.

- Helmholz- would love to see someone's solution to drone using this...

- Heavier gauge steel exhaust pipes? People like the 'light weight' of aftermarket systems, but maybe that heavy steel helps dampen drone...

- Header wrapping around pipes? I wonder if this could help?

- Stock muffler had a rubber damper thing attached to the front... I wonder if something could be done like that.

Anyway I'm ok with my setup now, but I miss the stock refinement.