LT1 Cutlass 2.5" or 3" exhaust

[454muscle]

Go with 2.5" and since you're putting on Flowmaster 40s I also recommend you do at least two more things:

1) 3" (or even 4") tips, the longer the better (ie. 24" is perfect)
2) H-pipe

The h-pipe (and not the x-pipe) along with the tips, (along with your engine setup) will give you a sound that will blow your mind. Trust me -- you'll thank me later.

 

[pontiacgp]

I have 2.5" SS exhaust with Headman Elite headers, twin high flow cats and 2 SS magnaflow mufflers.....I ran with the mufflers for about a month before I put the car away for the winter and the mufflers are coming off and going up for sale and will be replaced with something quieter. I don't have a need for that kind of sound just to attract people and it bothers me when I open it up. I can get a nice SS turbo muffler that will give me the sound I like without any performance loss.

 

[bigdan]

3" is for big blocks such as 454 no need for this on a SBC .....

, 3" exhaust would cut power in the lower range .....good mandrel bend exhaust system on 2.5" is top, for your use !

when i ordered mine, I had the choice for same price ....
space is a factor also 3" will rub everywhere ....

I have a similar set up to yours ...still wondering about my engine harness ;-(

 

[FE3X CLONE]

My exhaust guy said it would be hard to run 2.5 over the axle cause it risks getting pinched because of suspension travel.

I ran 3" pipes over my axles without any problems. 2.5" is a cake walk!

 

[Blake442]

My exhaust guy said it would be hard to run 2.5 over the axle cause it risks getting pinched because of suspension travel.

I ran 3" pipes over my axles without any problems. 2.5" is a cake walk!

X2! I have 3" all the way back from the headers to the tail pipes.

 

[454muscle]

My exhaust guy said it would be hard to run 2.5 over the axle cause it risks getting pinched because of suspension travel.

I ran 3" pipes over my axles without any problems. 2.5" is a cake walk!

X2! I have 3" all the way back from the headers to the tail pipes.

X3! What the hell, I'll jump on too lol. I have 3" mandrel bent pipes all the way back over my axle too! 😀

 

[pontiacgp]

Or you can run 2.5 to the mufflers then 2.25 past the mufflers so you have plenty of clearance over the axle tubes. My exhaust guy said it would be hard to run 2.5 over the axle cause it risks getting pinched because of suspension travel.

he was probably talking about some good SS tubing....the common cheaper aluminized tubing is easier to bend....

I got mine done by a shop that does alot of custom work and they did my car 2.5" SS front to back but they said 2.5" was about the largest for my car they'd try...plus my car has lowered suspension so that gives it less room

 

[megaladon6]

if you buy a properly made kit, there should be zero fitment issues with 2.5. my pypes kit went in very easily.

 

[FE3X CLONE]

Most exhaust shops can't bend anything bigger than 2.5" pipe. When they try 3", it ends up crimping the tube too much. However if you buy pre-made mandrel bent exhaust pipes, there's no problem.

 

[Doober]

if you buy a properly made kit, there should be zero fitment issues with 2.5. my pypes kit went in very easily.

Mine too, I'd buy another in a heartbeat! 8)