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      07-30-2018, 03:05 PM   #1
AriuSen
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Need ideas for quieter exhaust sound

So I have a custom diffuser that covers the whole rear bottom of the car. The RPI clears but my few mm so I installed a new muffler that looks similar to RPI but a lot thinner. The problem is both are too loud so I hope you guys can help me.

I need a universal or aftermarket muffler that it's thin enough to clear my diffuser but at the same time I wanna keep it quieter than RPI.
Do you guys know any universal valvetronic muffler?
Should I add resonators on section 1?
I don't mind the muffler being single pipe.
I already know that I will need some custom work.
Thanks for your help.
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      07-30-2018, 04:44 PM   #2
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I have Eisenmann Sports, they're a whole lot smaller than stock. No more gonads hanging under the back of the car.
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      07-30-2018, 04:57 PM   #3
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Quote:
Originally Posted by wdb View Post
I have Eisenmann Sports, they're a whole lot smaller than stock. No more gonads hanging under the back of the car.
Hmm they are still pretty big compared to RPI
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      07-31-2018, 12:13 AM   #4
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Quote:
Originally Posted by AriuSen View Post
Quote:
Originally Posted by wdb View Post
I have Eisenmann Sports, they're a whole lot smaller than stock. No more gonads hanging under the back of the car.
Hmm they are still pretty big compared to RPI
Yep. You're going to need some kind of muffler built in upstream of the diffuser. That's a tough nut, as space becomes an issue unless you use the space where cats were. Cats serve as sound reducers, and I don't know if you can reduce sound without some flow/power restrictions. That's above my pay grade lol.
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      08-01-2018, 06:46 AM   #5
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Varex mufflers have a built in valve , you could even open it at certain Rpm or speed .
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      08-01-2018, 02:02 PM   #6
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I just changed out my Magnaflow 6" 5x8's for a pair of Kooks that are 10" long but 4x8. The race Magnaflows were too loud. I was measured at 106 db. The Kooks sound good and are much quieter. Summit Racing carries them. I'm using 2 1/2" single in/out. My setup is custom so it's all tucked up nice. These fit really well.
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      08-27-2018, 11:40 AM   #7
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Quote:
Originally Posted by ///Mcoupe View Post
Varex mufflers have a built in valve , you could even open it at certain Rpm or speed .
Thanks. will look into it.
I bet they wont have a muffler as small as RPI thought to clear my diffuser.
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      08-27-2018, 11:41 AM   #8
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Quote:
Originally Posted by Michael9218 View Post
I just changed out my Magnaflow 6" 5x8's for a pair of Kooks that are 10" long but 4x8. The race Magnaflows were too loud. I was measured at 106 db. The Kooks sound good and are much quieter. Summit Racing carries them. I'm using 2 1/2" single in/out. My setup is custom so it's all tucked up nice. These fit really well.
Thanks Michael!
Would this be the one that you got?

https://www.summitracing.com/parts/k...0-14/overview/
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      08-28-2018, 11:00 AM   #9
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Alex, how about the stock ones with the baffels removed? Seems to be a very popular mod across the pond innPommy land.
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      08-28-2018, 12:28 PM   #10
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Alex, how about the stock ones with the baffels removed? Seems to be a very popular mod across the pond innPommy land.
oem muffler is way too big though lol
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      08-29-2018, 07:22 AM   #11
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Do you have much space left between the diffuser and the RPI's? Could you get a local exhaust shop to replace the silencers for some bigger ones?

It would be ideal to keep the silencers as far rearwards in the exhaust system where the volume flow would be lower.
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      08-29-2018, 01:28 PM   #12
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Originally Posted by just-right View Post
Do you have much space left between the diffuser and the RPI's? Could you get a local exhaust shop to replace the silencers for some bigger ones?

It would be ideal to keep the silencers as far rearwards in the exhaust system where the volume flow would be lower.
nope....i have a hair of space lol.
I will check if there is a way I can lower the diffuser a little more.
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      09-11-2018, 03:32 PM   #13
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Quote:
Originally Posted by AriuSen View Post
Thanks Michael!
Would this be the one that you got?

https://www.summitracing.com/parts/k...0-14/overview/
Nope. This one:
https://www.summitracing.com/parts/k...0-12/overview/

I thought they were 10". I guess they're 12". I believe they're even quieter than the 14" 5x8 single in dual out mufflers that came with my old BMS exhaust. Very tolerable for a track car. And that's without cats and a highflow 2.5" exhaust.

They sound really good. Higher quality construction compared to Magnaflow. They're show worthy.
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