I have a 79 T/A and i'm trying to deside what size exhaust to get.

I have a 462 http://forums.performanceyears.com/g.../icon_cool.gif

#62 heads lightly ported
KB pistons 9.5-1 compression
stock 44bl intake
44bl Quadrajet
cam close to 068 with 1.65 roler tip
hedman 1 3/4 headers

This engine will be a strickly street use car.

I would like good air flow, but don't want to hurt my back pressure.

Will 2.5 be enough? I was thinking 3" because of a chart p-dude has on this website.

I have a 79 T/A and i'm trying to deside what size exhaust to get.

I have a 462 http://forums.performanceyears.com/g.../icon_cool.gif

#62 heads lightly ported
KB pistons 9.5-1 compression
stock 44bl intake
44bl Quadrajet
cam close to 068 with 1.65 roler tip
hedman 1 3/4 headers

This engine will be a strickly street use car.

I would like good air flow, but don't want to hurt my back pressure.

Will 2.5 be enough? I was thinking 3" because of a chart p-dude has on this website.

Also. Is it worth getting an X or H pipe?

more specs

M21 transmission
3.42 gears
255/60/15 tires

H pipes are cheap and worth the trouble. X pipes are more expensive and more difficult to fit in an existing exhaust system so you need to be sure you really need one. I have a feeling that on a mildly tuned 400 or a relatively stock 455 engine that it doesn't make much of a difference.

I'd stay with 2.5 with how mild your combo is unless you want a real deep rumble. You probably wouldn't see any perforance gains 3" but it does sound real cool. Also an H or X pipe can quiet your exhuast some if it ends up being louder than your neighbors want.
Bartman

Ponies run but Birds fly

A properly designed 3" system with X pipe shouldn't hurt your backpressure, plus you'll be ready if or when you want to do some upgrades to your 462.
I have a 3" system with X pipe on my basically stock HO 400 '67 GTO and have experienced no downside. I am currently using the HO manifolds with 2.5" downpipes tapered to the 3" headpipes. This system was installed in anticipation of a moderately built 462 going in at a later date.
All tests I have seen have shown the X-pipe making more power than the H-pipe and it does quieten it down some. As stated above though, it will be more difficult to fit on a system already in place.

Sixties Guy,

Your the first person Ive heard that did not say that 3" was overkill for a street car. I put full 3" on my 66 with a cross over and 2" headers (467) and alway's wondered if I made a mistake. I never ran the car with anything else so I couldn't tell if it was helping or hurting me. http://forums.performanceyears.com/g...n_rolleyes.gif

I'm glad to hear your opinions,they answer just one more of the many questions I have. http://forums.performanceyears.com/g.../icon_cool.gif http://forums.performanceyears.com/g.../icon_cool.gif http://forums.performanceyears.com/g.../icon_cool.gif

All good things are worth waiting for. "Yeah right", I want them now!

"Artificial intelligence is no match for natural stupidity".

Sorry, I ment x-pipe not cross over. http://forums.performanceyears.com/g...n_rolleyes.gif

me bad http://forums.performanceyears.com/g...icon_frown.gif

All good things are worth waiting for. "Yeah right", I want them now!

"Artificial intelligence is no match for natural stupidity".

Bob,
My system was purchased from the Buick GS Club and was specially made for them by Hedman. Of course it will fit all GM A-Bodies so it worked well on the GTO. The club newsletter was filled with positive feedback on the system so after a few months of reading about them, I ordered one and have been well pleased. As stated earlier, I have a basically stock 400 HO with 4 spd. and 3:23 gear. I can still lug down in 4th gear, don't have to downshift to pass, just kick in the secondaries and go. I am running 2.5" outlet HO manifolds and 2.5" downpipes tapered to 3" headpipes. Am also running DynoMax Ultra-Flo Welded mufflers.
I firmly believe the x-pipe and Pontiac's traditional torque output are the major factors in keeping the 3" system a viable street option.

I'm thinking i'll go with the 3" with an X Pipe. I know this might be a little much, but I do plan on upgrading in the future and I don't see how it could hurt me either. I'm still thinking about it.

Thanks for all the replies! http://forums.performanceyears.com/g...icon_smile.gif