Stopping the knock: Lower compression and ported heads...

Correct-most of the time, unless it's a commonly used thickness, Cometic makes them per requested spec. I was fortunate with my 4.6 4V build that Fel-Pro also makes MLS gaskets for that app. Before you lay them down though, is your deck surface machined with the proper RMA to use Cometic gaskets? I'm thinking this has been covered before in previous threads, but I can't recall.