Which Header Gaskets should I use on a GT40 heads?

Copper gaskets are good but they are the most expensive. I havent had any problem with regular header gaskets made by fel pro.

Use the Fel Pro Performance gaskets. I think they're part number 1215. Most Checker Auto stores have them. I know since I work there! :winks

Use the Ford expanded grahite head gaskets they are the best and not too expensive,you can get then at summit or ford dealership.These gaskets are a little thinner so it up you compression a little.

All the above gaskets will work. The secret of getting a good seal is not in the gasket, but in the fastener and the torque applied.

I found some hardened aircraft fasteners complete with studs and hardened self locking nuts on Ebay for less than 20 bucks! :eyepoppin

Aluminum alloy and no rust!

i have bbk long tubes with gt40 heads, i did use the felpro gaskets but every month i would develope an exhaust leak. finally installed copper gaskets and bought the stage 8 locking header bolts, havent had a problem in 6 months.