So right now I have exhaust manifolds on my 289. I'd like to get some headers, I'm thinking of the Tri-Y variety. I already have an upgraded intake and exhaust, (air filter, carb, intake manifold, tailpipes, mufflers, ect...) the headers are just kinda the last step. Can anyone give me an estimation on how much of a horsepower gain I would experience? i know it's different for each application, but does anyone have a ballpark guess?

 

cant help with your question other than to tell ya to buy some with a thick flange

the cheapies suck (and leak)

 

I was thinking of buying tri y headers too...is there a huge difference in quality between the black ones and the ceramic ones ? Will the black ones rust out?Do they come with the thick flang?

 

From experience, (if you decide to go with headers) I would highly recommend headers that are ceramic coat, jetcoat, etc. over the black.

 

I'd have to guesstimate maybe 10-15hp on a set of tri-y's over stock manifolds. Tri-y's and an intake/carb were the only real differences between the 289 hi-po and Shelby's GT350 engine. It wasn't a waste of money for the GT350, and I don't think you'll consider it a waste once you have them

Another option would be a set of hi-po manifolds. They won't flow quite as well (especially at higher rpm's) as tri-y's, but the engine bay will be much quiter and cooler.

If you do go with headers, go ceramic coated. It's the only coating that's going to last, and it helps keep heat inside the tubes and out of the engine bay.