Sidepipe horsepower loss?

[rdc767]

Guys looking for some advice. I did a dyno run last week with less then stellar results. 295hp / 383cu/in sbf

Looking through my setup and I going to change a few things.

Port match the headers or at least work the welds and smooth them out.

Possible change the glasss packs out in the sidepipes or take them out.

Taller manifold (victor jr.) and port match the heads. Current is a low dual plane. Current carb is a Edelbrock 750 cfm

Don't really want to change out the cam. It has a hydraulic flat tappet with 500/520 lift. Heads are procomp aluminium 2.02/1.60 valve. Compression is around 10.5/1. Max timing was 36 degress. a/f ratio was a bit rich 12.5 to 1.


My question is can you go too large in the inside diameter of the glasspack? I was thinking of taking them out and just using a thin fiberglass sheet and metal screening. (dont care about noise). Aft of the collector is 3.5" I would use a 20" turnout the same size 3.5".

Is no restriction in the exhaust bad for HP? or the exhaust valves?

Thanks
Ron