Need Opinions on options for installing a 3" Exhaust System

**MopàrBCN** · 02-05-2008, 07:13 PM

Hi,

I am ready to install a 3" Exhaustsystem to my 89 TII Daytona. I have: 3" Downpipe, 3" Cat, 3" Mandrell Bend Pipes and a 3" Muffler.

Being the way I am, my normal choice would have been buying a 3" Swingvalve as well. But since both vendors whom I trust for oversees trading don't list them in their catalogues at present I figured that I have to fit it to my 2.5" Swingvalve. So far I am clear.

Now, having learned that using the 3" Donut on a 2.5 Swingvalve will most likely cause it to get damaged with time I started wandering how you guys go on about this.

Given the situation, I know, I have 3 Options:

1. Mating the 3" Downpipe to the 2.5" Swingvalve
2. Leave the 2.5" Downpipe as it is and start the 3" System up from the Cat.
3. Get a 3" Swingvalve (how and where???) And Install the System right from there.

So which of those Options would you opt for?
I am really interested in the outcome of this poll. I also think it will be interesting for others like me in a similar situation.

**87glhs232** · 02-05-2008, 07:25 PM

Call Chris W. at TU. He doesn't list them separately anymore, you have to go into the down pipe section and select it as an option when buying a 3" DP

Personally I would spring for a swingvalve instead of your other options. Chris may be able to sell you one, if not keep an eye out on the Forums. Post up a wanted ad too.

**tryingbe** · 02-05-2008, 07:28 PM

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**BadAssPerformance** · 02-05-2008, 07:57 PM

I used a 3" DP on a 2.5" swingvalve for years w/o issue, just need to make sure you have a good front motor mount so that the engine doen not slop around making that 3" exhaust donut gasket fatigue. Also, you can swap in the 3" swingvalve later on whenever you get one.

Also, FWIW, my T2 Shadow (CSX Clone) has a 3" (non-mandrel bent) with the stock Garrett 2.25" swingvalve and downpipe

**Birddog** · 02-05-2008, 08:48 PM

I have to chirp in on that tearing up the donut part too. I've had a 3" dp/donut on my 2.5" sv for over a year daily driven. Some of that time was on an open dp with no support too and it's still sealing and in good shape.

**GLHNSLHT2** · 02-05-2008, 09:16 PM

Ran a 3" donut on a 2.5" SV (ported hehe) for years now. While it does dent it as long as your motor isn't rocking around it'll be fine. I run a custom PB front mount, and a semi solid rear tranny mount. Semi as in only one side has poly, the other is metal to metal.