As part of my tuning up a EFI thread, I asked Matt at Matts about the whole argument for changing from EFI to carbs - his response was "there is no power advantage to be had changing from efi to carb,in fact a well set up efi wil give you slightly more than the equivalent carb set up."
Apparently he's the man. So, if its a question of extra performance, looks like working with an EFI may be the most profitable route, I'll continue on my EFI post
Cheers, Roy