C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Exhaust Advice Needed...

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Old Mar 15, 2009 | 01:42 PM
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Default Exhaust Advice Needed...

So I go out to the garage yesterday, to install my new Dynomax Super Turbos. Take the old system off, and a quick measurement reveals my 2.25" Y-Pipe isn't going to work with the new 2.5" mufflers.

So I go to Summit's website, and find the appropriate Dynomax Y-Pipe. 2.5", perfect. Nope, the Dynomax pipe is a 4 bolt flange, and my old one is a 2 bolt flange. So I'd have to change my converter as well.

My problem now, is finding a 2.5" y-pipe, with a 2 bolt flange. Obviously, I could change the converter out as well, but I really don't want to spend another $120+ there. A stupid muffler swap is adding up fast.

I have a hard time believing, that I'm the first person to run into this problem. Suggestions/Recommendations?
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Old Mar 15, 2009 | 02:07 PM
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I'd try a local muffler shop they may have adapters in stock or be able to make up some to go from 2 1/4 to 2 1/2...years ago most parts stores carried exh. adapters...I haven't seen 'em in years though, guess they're not as popular nowadays...may not look as pretty but it'd sure save over buying a new pipe and converter
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Old Mar 15, 2009 | 02:08 PM
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Can you use an adapter that goes from 2.25 to 2.5 so you can use the mufflers without changing the y-pipe? Autoparts stores sell them.
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Old Mar 15, 2009 | 02:09 PM
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I have no problem buying the new y-pipe. If anything, I'd rather install the bigger y-pipe. My problem is the converter.
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Old Mar 15, 2009 | 02:15 PM
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Originally Posted by Corvette Chris
I have no problem buying the new y-pipe. If anything, I'd rather install the bigger y-pipe. My problem is the converter.
Leave it out and turn it into a race car.
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Old Mar 15, 2009 | 02:19 PM
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Originally Posted by 383vett
Leave it out and turn it into a race car.
Please, don't tempt me like that!
Hmmm solid axle, cowl on the hood....
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Old Mar 15, 2009 | 02:21 PM
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Originally Posted by Corvette Chris
Please, don't tempt me like that!
Hmmm solid axle, cowl on the hood....
Gotta start somewhere!
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Old Mar 15, 2009 | 02:22 PM
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I'm not following the details exactly, but is there anything preventing you from just cutting off the offending flange, and then welding on the appropriate flange? I weld up all my own systems, and it ain't rocket science.
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Old Mar 15, 2009 | 02:24 PM
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Originally Posted by 69427
I'm not following the details exactly, but is there anything preventing you from just cutting off the offending flange, and then welding on the appropriate flange? I weld up all my own systems, and it ain't rocket science.
I've got a mig welder. Never used it before though. How easy is easy? Like first timer stuff?
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Old Mar 15, 2009 | 02:37 PM
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Originally Posted by Corvette Chris
So I go out to the garage yesterday, to install my new Dynomax Super Turbos. Take the old system off, and a quick measurement reveals my 2.25" Y-Pipe isn't going to work with the new 2.5" mufflers.

So I go to Summit's website, and find the appropriate Dynomax Y-Pipe. 2.5", perfect. Nope, the Dynomax pipe is a 4 bolt flange, and my old one is a 2 bolt flange. So I'd have to change my converter as well.

My problem now, is finding a 2.5" y-pipe, with a 2 bolt flange. Obviously, I could change the converter out as well, but I really don't want to spend another $120+ there. A stupid muffler swap is adding up fast.

I have a hard time believing, that I'm the first person to run into this problem. Suggestions/Recommendations?

The 4-bolt flange is intended for an 84-85 model. 86-91 use the 2-bolt. I looked at the Summit description and I think they have a misprint. The part# 40320 should fit your car. Try talking to one of the Summit reps.
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Old Mar 15, 2009 | 03:02 PM
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Originally Posted by Corvette Chris
My problem now, is finding a 2.5" y-pipe, with a 2 bolt flange. Obviously, I could change the converter out as well, but I really don't want to spend another $120+ there. A stupid muffler swap is adding up fast.
You spend $120 easily on a nice dinner for two with drinks if it meant getting the girl that you want.

Why not ante up and buy the new Cat? You get more performance and have something that keeps on giving performance everytime you start her up!
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Old Mar 15, 2009 | 11:23 PM
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Originally Posted by Rogue1
You spend $120 easily on a nice dinner for two with drinks if it meant getting the girl that you want.

Why not ante up and buy the new Cat? You get more performance and have something that keeps on giving performance everytime you start her up!
Forget about the cat. If you order a new 4-bolt cat, it will not connect to the front Y pipe slip fitting. Then you'll have to replace the front Y as well (another $200). Walker (Dynomax) makes the correct 2.5 inch rear Y and it has the balance tube to reduce drone.
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Old Mar 16, 2009 | 12:41 PM
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Just ditch the cats and take your car to hole in the wall shops for inspection so they dont care about emmisions. I dont have to worry about emmisions as much down here (thank god) so that was the first thing i did to my car!
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Old Mar 16, 2009 | 05:28 PM
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Walker Dynomax PN# 40320 is in fact a 2-bolt flange. Called and talked to Summit about it earlier, and the rep confirmed it.
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Old Mar 19, 2009 | 04:56 PM
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I believe the 40320 y-pipe is 2.25" as it's meant to be a stock replacement and works with the dynomax 17760 and 17761 mufflers, which are also 2.25" inlets.
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Old Apr 11, 2009 | 01:36 PM
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How does your car sound with the Dynomax. I was thinking of B&B but need to save some money as I just had to put a clutch in the car (96 LT4). The stock exhaust is way to quiet
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Old Apr 11, 2009 | 03:02 PM
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Originally Posted by jeffnoa
How does your car sound with the Dynomax. I was thinking of B&B but need to save some money as I just had to put a clutch in the car (96 LT4). The stock exhaust is way to quiet
Haven't really had it running that long with the new system. It did sound good the few minutes I had it running though. Fighting a fuel rail leak with this stupid cold start injector. Once thats done, I'll have a better review.
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