Exhaust from Valve Cover Bolt Holes?
 

I'm getting exhaust coming from all the bottom valve cover bolt holes on both sides of the engine. If the bolts are in the holes it doesn't leak exhaust, but I forgot one while changing covers and found the problem. I don't think its crankcase pressure either. With the bolt out it sounds just like an exhuast leak. tap tap tap. The heads are TF High Port heads and have never had a problem with them in the past. Car still runs fine and has power. Whats the diagnosis?

Sounds like the hole is drilled through to the exhaust port. Not a big deal, just leave a bolt in there ;)