As for hot air getting into the engine bay due to the FMIC, why dont you flip your csoop backwards for the time being. It wont look amazing but will vent off the hot air. Just a thought.....
(This is aimed at Iain aka guru primarily!) How easy is it to port the headers and up-pipe to improve flow and what are the pitfalls? I have got hold of a classic up-pipe and 03 headers for £15!!!! Thought it might be another good upgrade on the path to enlightenment!