I cut out just about double the cylnder head area and have no cooling issues. I also have some extra air flow over the muffler as it was running really hot. ST 90 2C 10% MA 14X6 max OAT so far 32C.

My engine is also at the inverted angle and its not bad for starting. Just go WOT for a few flips to clear it and then she starts right up.

Quick vid for what its worth. Wasn't set up quite right but gives the idea. I've since gotten braver, much braver
http://www.rcgroups.com/forums/showt...83#post5768198