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      05-27-2012, 11:00 AM   #1
Raptor251
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The Perfect Note!

As we all know the e9x exhaust note is a very subjective thing. I have tried many different combos in my quest for the perfect sound. Most recently I added an H pipe to my RPI mid pipe. The addition of the H pipe really changed the sound of the car. I couldn't be happier except the car now has a little bassy resonance. After many conversations with Jim @ Lyons Muffler (the exhaust master!) he made a great point and that is the mufflers are acting like megaphones. Each muffler has a single inlet but dual outlet acting as a megaphone increasing the drone and resonance coming out of the tail pipes.

Enter Dinan...The Dinan mufflers IMO produce the cleanest sound around with almost no drone and they have one inlet and one outlet! The mufflers have dual tips but one set is fake. The problem is being catless really stains the working chrome tips and the dummies stay mint. So got the idea to try to reduce the outlet diameter on two of the four tips. The logic is the reduction in outlet diameter will reduce the megaphone effect. The Fabspeed mufflers have the two outlets pulling from the same main chamber so I wasn't worried about effecting exhaust flow as the mufflers would still allow more exhaust to leave the mufflers than enter them. So I pulled off two of the four tips, found some washers that fit snugly inside the outlets pipes and tacked them in. The washers have a 3/4" inside diameter reducing two of the four tips down form 2 1/4"

My concern was it might create a whistling effect but it didn't! The plan worked and it worked really well! The drone has been eliminated and the note is really clean! Best part of all is all four tips still work and I dont have the Dinan dummy syndrome. And after driving the car all day yesterday I cant notice a single difference in power. I really cant believe how well this worked and it cost me $1.08 for two fender washers! I just wanted to share my findings as it's amazing. I included a close up pic to see what's going on and just an FYI you cant see the washer unless you shine a flashlight in the tail pipe and look for it!
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      05-27-2012, 12:44 PM   #2
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Nice. Can't wait to hear.
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      05-27-2012, 01:02 PM   #3
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Very interesting. I would imagine this would create a tad more backpressurre, but nothing that would be measurable.
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      05-27-2012, 01:41 PM   #4
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Quote:
Originally Posted by Stealth ///M View Post
Very interesting. I would imagine this would create a tad more backpressurre, but nothing that would be measurable.
Yeah I'm not quite sure but there is only one 2.5" pipe coming in to the back of the muffler and that is not being touched.

And Tech I would love for you to drive my car and see what you think about my mutant exhaust!
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      05-27-2012, 01:53 PM   #5
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That is a really great idea, kudos for thinking out of the box and further, acting on it.
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      05-27-2012, 06:14 PM   #6
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Quote:
Originally Posted by crabman View Post
That is a really great idea, kudos for thinking out of the box and further, acting on it.
Thanks for the props! And FYI I changed out the washers today with ones that have a 1/2" diameter hole instead of a 3/4'' and it toned the sound down just a tad bit more to where I couldn't be happier!
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      05-27-2012, 07:30 PM   #7
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Video with sound ?
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      05-27-2012, 08:05 PM   #8
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Is this still the stock muffler?
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      05-27-2012, 11:36 PM   #9
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great thinking man! I'll have to give that thing a listen for sure
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      05-28-2012, 02:41 AM   #10
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I would imagine this would create a tad more backpressurre
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      05-28-2012, 09:45 AM   #11
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VIDSSS!!!
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      05-28-2012, 10:27 AM   #12
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Quote:
Originally Posted by Stealth ///M View Post
Is this still the stock muffler?
"The Fabspeed mufflers have the two outlets pulling from the same main chamber so I wasn't worried about effecting exhaust flow as the mufflers would still allow more exhaust to leave the mufflers than enter them. So I pulled off two of the four tips, found some washers that fit snugly inside the outlets pipes and tacked them in."
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      05-28-2012, 10:40 AM   #13
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Quote:
Originally Posted by DorethaRockl View Post
I would imagine this would create a tad more backpressurre
Please explain, the way I look at it is I'm not messing with the flow because each muffler still has a 2.5" inlet and a total of 3 inches of outlet. While I do agree I'm creating more back pressure, I would also argue it cant have a negative effect on the cars performance because the outlet diameter is still greater than the inlet.
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      05-28-2012, 11:49 AM   #14
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Nice thinking
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      05-28-2012, 12:41 PM   #15
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Quote:
Originally Posted by SehrSchnell View Post
Lets hear it!
Alright, alright...Just got the GoPro out and I'll make a little vid.
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      05-29-2012, 01:05 AM   #16
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I'm in to hear this one! Very interesting!
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      06-11-2012, 10:49 AM   #17
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Any updates? Vids?
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      06-15-2012, 09:32 AM   #18
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I did my own stock exhaust mod for free and it is producing what I would consider the "perfect" note.

In for a sound clip (or better yet, hear it in person since video usually doesn't quite capture it)
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