I have this stuff done to my 85 'bird with a built 355:

Comp Cams Magnum 280H cam kit (230/230 @ .050 .480/.480 lift)
Ported & Polished Heads
Edelbrock Performer RPM intake manifold
Edelbrock 750 CFM 4bbl carburetor
Flowmaster muffler

But I'm still running the little stock manifold that came with the original 85 4BBL 305 and stock y-pipe with a gutted cat. Am I missing out on a lot of performance?

I have a set of shorty truck headers that should fit with a custom y-pipe (or true duals). What kind of performance gain (HP or 1/4 mile) would I get from 1 5/8" tubular shorties on a setup like this?

Thanks

 

Um.......YA!!!
You have a pretty sweet setup get some 1 3/4 headers and you will probably get at least a few tenths in the quarter.

Brian

 

Absolutely restrictive--even on a stock engine. Dump them.

JamesC

 

I had a 305TPI with a cat-back and afpr.
stock manifolds and gutted cat.

I swapped in shorty headers and had an exhaust shop make up a Y-pipe for me with no other changes made.

I never got any track times butt I could feel more pull throughout the rpm range and a lot more top end power.

That was on my stock (non-peanut) cammed 305/T-5

I'm sure you will feel it even more on a 355 with an aftermarket cam.

DO IT

Hodge

 

if you dont get headers, i will personally hunt u down and attack you!:lala:

 

go with headers for sure increases can be had in the over 20hp range