Heat isn't really much of an issue. 1.8T TTs have the same insulation but they removed it for the V6, I can only guess this was for sound but the
problem is it allow condensation to bulid up on the under side & then drip on the engine, on the V6 TT this causes problems as the water drips onto the coil pack plugs & gets down into the plug holes causing all sorts of missfire problems.
End of the day I'd say its not worth it, if you want to let more noise out remove the rubber seal along the top of the bulkhead/scuttle trim, this increased the induction & recurc vavle noise quite a bit on my S3 with an open filter, should
help let out a bit of engine bay heat aswell which can only be a good thing.
Cheers Ewan.