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Rev9 Exhaust

Supermoto

Autocross Champion
Location
San Diego
Car(s)
2019 Autobahn DSG
my advice would be to just get the first resonator cut out, then replace that with the new vibrant res. I wouldn't worry about the 2.5" to 3" part as you do need to have a spot where you can disconnect dp and catback or else if its 1 whole thing, its never gonna go into car or out lol. So really I don't think its worth it to just modify the small 2.5" part of the downpipe to make it 3

I want to remove the reduced section mainly cause with how it is set up now, theres quite a few exhaust leaks coming from that mess of reducers and clamps (and im just OCD like that :LOL:). I was planning to cut the reduced end off the downpipe and catback and welding a 3 inch section to the catback then clamping that to the downpipe. Speaking of welding, considering people earlier in the thread saying how this isnt a "true" 304 stainless system due to it being magnetic, would it be that risky to weld it using steel wire and just paint over the welds with exhaust enamel to prevent rusting?
 

mk7_bk

Autocross Champion
I want to remove the reduced section mainly cause with how it is set up now, theres quite a few exhaust leaks coming from that mess of reducers and clamps (and im just OCD like that :LOL:). I was planning to cut the reduced end off the downpipe and catback and welding a 3 inch section to the catback then clamping that to the downpipe. Speaking of welding, considering people earlier in the thread saying how this isnt a "true" 304 stainless system due to it being magnetic, would it be that risky to weld it using steel wire and just paint over the welds with exhaust enamel to prevent rusting?
I get what your saying, i think yeah you can cut the 2.5 section of the downpipe, but then its worth way less if you ever want to sell as it now wont fit any stock car. Always gotta think about the future too. I do think it is a little messy with the whole way its setup. Interested to see how it fits, if you have 3" downpipe end, then the vibrant which can slip over both 3" sides, and then just remove the whole first res.

DP 3"end | Vibrant res | 3" pipe (no res total cut), i mean this will work yes. just wont have easy time to resell dp if you go that route.
 

Supermoto

Autocross Champion
Location
San Diego
Car(s)
2019 Autobahn DSG
I get what your saying, i think yeah you can cut the 2.5 section of the downpipe, but then its worth way less if you ever want to sell as it now wont fit any stock car. Always gotta think about the future too. I do think it is a little messy with the whole way its setup. Interested to see how it fits, if you have 3" downpipe end, then the vibrant which can slip over both 3" sides, and then just remove the whole first res.

DP 3"end | Vibrant res | 3" pipe (no res total cut), i mean this will work yes. just wont have easy time to resell dp if you go that route.

Hell, my downpipe is a 99 dollar ebay downpipe that I got for free, its worthelss hahaha. Perhaps I will start with trying to throw the new res in there to join the DP to the catback and leave the first rev9 res where it is (assuming theres enough room. If I determine its too quiet or something I can always cut out the Rev9 res. Regardless I will update once whatever I end up doing is complete.

Edit: Should I use high temp RTV or muffler cement on all the clamped joints to seal it up? I have both on hand.
 
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mk7_bk

Autocross Champion
Hell, my downpipe is a 99 dollar ebay downpipe that I got for free, its worthelss hahaha. Perhaps I will start with trying to throw the new res in there to join the DP to the catback and leave the first rev9 res where it is (assuming theres enough room. If I determine its too quiet or something I can always cut out the Rev9 res. Regardless I will update once whatever I end up doing is complete.

Edit: Should I use high temp RTV or muffler cement on all the clamped joints to seal it up? I have both on hand.
I didn't use any muffler cement or anything just tighten the clamps
 

Supermoto

Autocross Champion
Location
San Diego
Car(s)
2019 Autobahn DSG
Alright so I have been working on getting the res installed, and I noticed that the catback doesnt sit straight. The end that connects to the downpipe is not parallel to the end that connects to the muffler under the rear suspension. This is causing the downpipe and resonator to be pulled toward the wall of the tunnel under the car, making it impossible to fit the vibrant res. I am going to spend more time on it today to see if I can get it all to fit with clamps and some adjusting, but I think I am going to need to weld it so I can tweak things to fit properly. Pretty unfortunate.
 

mk7_bk

Autocross Champion
Alright so I have been working on getting the res installed, and I noticed that the catback doesnt sit straight. The end that connects to the downpipe is not parallel to the end that connects to the muffler under the rear suspension. This is causing the downpipe and resonator to be pulled toward the wall of the tunnel under the car, making it impossible to fit the vibrant res. I am going to spend more time on it today to see if I can get it all to fit with clamps and some adjusting, but I think I am going to need to weld it so I can tweak things to fit properly. Pretty unfortunate.
while I was under my car, the long middle pipe seems to be very straight down the middle, maybe your downpipe is a bit twisted?
 

Supermoto

Autocross Champion
Location
San Diego
Car(s)
2019 Autobahn DSG
while I was under my car, the long middle pipe seems to be very straight down the middle, maybe your downpipe is a bit twisted?

Funny enough, for a 99 dollar ebay downpipe that I fabricobbled together its perfectly straight and centered down the tunnel. After putting everything together again, I am certain it is the rear portion of the catback that isnt alligned properly.

I managed to get everything to fit including the Vibrant res, and clamped up really damn tight. The res is quarter inch away from the right side of the tunnel, I am certain that as things settle it will start touching and create a rattle. Stainless mig wire is coming in the mail, so I will weld it all up to get some more adjustment out of it.

My current issue is still drone. As expected with a downpipe and catback, drone was going to be an issue. However, even with the vibrant res there is still significant drone right at 2.5k-3.2k rpm. I do have a catless downpipe, so its possible a catted DP would help tame this. There used to be a lot more drone throughout the rev range, now its just right at that sweet spot so many of us have come to know. It is driveable, however a lot of time is spent around 2.5k since its the shift point when you arent putting your foot down so the drone is definitely encountered often. I will look into downpipe options.
 

CarolinaPanthers

Ready to race!
Location
Bethlehem, PA
Car(s)
18 GTI 6mt
@Supermoto I’m in a similar boat. Clamped in Vibrant resonator, but to a AWE Track exhaust, and am experiencing drone in the same RPM range.

From a different thread, a knowledgeable member suggested clamping instead of welding is the root cause of the drone problem.
 

Subliminal

Autocross Champion
Location
Vegas
Car(s)
Slow FWD VW Hatch
Funny enough, for a 99 dollar ebay downpipe that I fabricobbled together its perfectly straight and centered down the tunnel. After putting everything together again, I am certain it is the rear portion of the catback that isnt alligned properly.

I managed to get everything to fit including the Vibrant res, and clamped up really damn tight. The res is quarter inch away from the right side of the tunnel, I am certain that as things settle it will start touching and create a rattle. Stainless mig wire is coming in the mail, so I will weld it all up to get some more adjustment out of it.

My current issue is still drone. As expected with a downpipe and catback, drone was going to be an issue. However, even with the vibrant res there is still significant drone right at 2.5k-3.2k rpm. I do have a catless downpipe, so its possible a catted DP would help tame this. There used to be a lot more drone throughout the rev range, now its just right at that sweet spot so many of us have come to know. It is driveable, however a lot of time is spent around 2.5k since its the shift point when you arent putting your foot down so the drone is definitely encountered often. I will look into downpipe options.
Noico 80mil in the hatch area and under rear seats helped a lot. A hi-flo cat does help quiet it down a bit too AFAIK.
 

Klrider44

Go Kart Champion
Location
Bucks county PA
I cut out the 2.5” section so it’s 3”all the way. Removed the first big resonator and had the vibrant welded in. Drone was definitely reduced but it’s still there from about 2,500 to 3,200. I have the catless rev9 downpipe as well which I bet is the big culprit here for the drone. I’m not gonna modify the exhaust anymore as it’s not a daily driver and it’s tolerable at this point. The drone is at its worst under boost, not bad at all when just taking it easy, and under 2,500 it’s very quiet.
 

Supermoto

Autocross Champion
Location
San Diego
Car(s)
2019 Autobahn DSG
@Supermoto I’m in a similar boat. Clamped in Vibrant resonator, but to a AWE Track exhaust, and am experiencing drone in the same RPM range.

From a different thread, a knowledgeable member suggested clamping instead of welding is the root cause of the drone problem.
I feel like I read that somewhere as well, however I dont see how it could make that big of a difference if all the clamps are tight. Either way, at this point I have nothing to lose so I will be welding the majority of the system next week when the stainless wire arrives. I might try moving the vibrant res closer to the downpipe.

Noico 80mil in the hatch area and under rear seats helped a lot. A hi-flo cat does help quiet it down a bit too AFAIK.
I have worked with noico in the past when covering the entire inside frame of a MX5, its good stuff. However from my experience it doesnt tend to help with exhaust drone very much as drone is a resonation of the entire frame due to the exhaust frequency. Its a possibility though.

Pictures supermoto? I do know the second piece that goes in curves and the tail of the first piece curves but idn
The whole system is installed right now for testing, but when I have it out next week to weld I will take pics.

I cut out the 2.5” section so it’s 3”all the way. Removed the first big resonator and had the vibrant welded in. Drone was definitely reduced but it’s still there from about 2,500 to 3,200. I have the catless rev9 downpipe as well which I bet is the big culprit here for the drone. I’m not gonna modify the exhaust anymore as it’s not a daily driver and it’s tolerable at this point. The drone is at its worst under boost, not bad at all when just taking it easy, and under 2,500 it’s very quiet.
I still have to remove the 2.5" section, besides that I have the same setup as you. For me though, the drone comes on strong at 2.5k regardless if im under boost or not, its just a lot worse under boost. As someone else said, welding the system might make a difference so I will be doing that soon, cause at this point I don't have much to lose. My downpipe is kinda hacked together and I was planning on replacing it in the future, so maybe when that day comes the drone will die down.

Edit: After research, I am heavily considering a 1/4 wave resonator. It would need to be around 20.5 inches and theres room in the front part of the tunnel. Not sure what diameter to make it out of, but welding a 90 degree J bend to the side of the exhaust and extending it to be a total length of 20.5 then capping it should solve the issue of the drone patch at 2.5k rpm.
 
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Subliminal

Autocross Champion
Location
Vegas
Car(s)
Slow FWD VW Hatch
The Noico helped with the vibrations and rattles caused by the drone. It's much more tolerable now
 

Supermoto

Autocross Champion
Location
San Diego
Car(s)
2019 Autobahn DSG
The Noico helped with the vibrations and rattles caused by the drone. It's much more tolerable now

Fortunately I dont have any rattles or excess vibration yet, just a loud head-filling bass note. I took out the heat shield above the rear mufflers and it did help a touch, but theres more that needs to be done. I will weld the system this week and am playing with the idea of a Helmholtz resonator.
 
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