Very dissapointing numbers after I replaced the exhaust. Base numbers were 141hp/228tq. After Headman shortie headers, y-pipe, and hooker catback it only gained very small numbers. 148hp/231tq. It was running richer than before. I was expecting alot more with the exhaust considering the previuos owner had put a 2 1/4" piece of pipe in place of the convertor and it had a stock muffler on it. I have a summit TPI cam kit and AFPR to put on. When I got the car it had 200-220 psi of compression on all cylinders cold. I havent put 200 miles on it yet. Are these numbers just me or do most of the 86 tpi just dont like anything with the stock cam?
If I'm not mistaken,I think 86 had the worst peanut cam ever in a tpi 305.
TGO Supporter
The 86 TPIs did come with the peanut cam. The exhaust will be worth it after you swap the cam. When new an 85 IROC with 305 TPI and better cam registered 180 RWHP @ 4000 RPM in an ancient Popular Hot Rodding article I have.
Yeah I know about the peanut cam. I just figured it would have made more than it did. Really sucked when I was hoping for about 15-20 more hp.
Supreme Member
I'm not sure it would make much differance with the stock 86 cam but.... Did you mod the hedman y-pipe? I believe the y has a 2.5 inch collector.