timothypaul

Hey Folks - I am contemplating redoing my exhaust.

Its a 455 CID - moderately worked. - Using Doug's headers.

My buddy has a 66 GTO w/ a 455 and he insists I need to go with a 3 inch exhaust.

Wondering for the extra money - is it worth it.

Thanks...TP

Erinyes

Try this thread...

MDchanic

Well, if you're making 680HP, then you need 3" pipes.

If you're "only" making 460HP, then 2½" pipes should be fine.

- Eric

Gunmars

I can't speak for the performance aspect of it or exactly what year of car you are putting it on. But if your going to buy 3" kit for A-body cars I would be cautious. I purchased 3" Flowmaster American Thunder kit for my 71 Supreme and had clearance issues even after modifications to the pipes. Another brand kit might be fine or you could always go custom bend to hopefully avoid this issue. Luckily for me I had a Chevelle which the kit fit amazingly and a 2.5" Flowmaster American Thunder fit perfectly out of the box.

Mikes65

2.5 will work and sound nice
Pypes street pro stainless steel- not polished- is a great deal

Kennybill

I would go with the 2.5" also, it's more than enough for your needs. I would put in a torque tube but it's your call. 3" is overkill and as one poster wrote, it can cause other problems. Kind of like opening up a can of worms. Good luck, Ken

matt69olds

I have the Torque Tech 3 inch system on my car, it fits great. It took a little effort to get it to clear in the front (I'm running a X pipe) but that is because of the Gear Vendor. It required the X a little further towards the rear of the car than would be normal.

brownbomber77

NOT worth it....you say "moderately worked", doesn't mean "race car", I'm assuming. The amount of noise and the cost of using a smaller pipe will make ya happy.

chadman

I have a 3" Torque Tech on my '65 w/Dynomax Super Turbo mufflers and a complete Pypes 2.5" Street Pro system on my '68. The '65 w/3" is actually quieter. With that said, unless you plan to make passes at the drag strip and run into the 11's I would go with the 2.5" system. I also prefer the Dynomax Super Turbo mufflers over the Pypes mufflers.

oldcutlass

I'd go with a 2.5 and install a set of exhaust cutouts if you want performance.

brownbomber77

Oh, yeah..turbo style mufflers, too...cheap...quiet...don't drone...maybe some people like drone...hmmm...