the soft gaskets seem to be popular. Copper or aluminum. But honestly, the key is doing it right. The header flange must be true and you need to torque them correctly and again after a few heat cycles. Ive had one set of thick paper gaskets on mine and they havent leaked yet. I put them on around 2004 or so but for about 5 years i didnt drive it much at all because I was active duty.