I think it's time to build a leak down tester and see what I come up with.  I'm really starting to wonder if there is a leak someplace now.

Any good threads or tutorials on how to build a leak down tester?  Also is there anything I need to worry about with the exhaust valve or any special things I should do or lookout for?  Do I need to remove any covers to check for leaks if I happen to have one that I can't see from the outside?