Quote Originally Posted by Vteckidd

Quick question, who on here has EVER seen a BURNED exhaust valve on an NA car?

I never have (unless the headgasket was blown and the engine melted down)
I have Chevy 305 two exhaust valves burned, it can happen but this wasnt due to headers or anything of the sort.

You guys are right though. scavaging is whats important. Back pressure isnt needed, it is what it says it is...pressure built up. It's not something you want. A good exhaust on lower hp cars will run better than just an open header usually becuase the longer open exhaust helps with pulling the exhaust gasses out vs. the open header. Now, you get to a high enough HP range and an open header would be fine due to the shear amount of gas comming out of the motor. If you have an open exhaust just leave it on and dont bother unbolting it and running just the header.