to chuck my ten pence in on the turbo thing as well, I went from turbo to n/a for my track car purely due to reliability reasons.
when a boosted engine is working, and working well, its a great laugh, but its just very expensive to get it working consistently reliably and not overstress everything else, particularly drivetrain. found mine usually lasted one or two track days before something needed replacing, upgrading or repairing.
with the n/a lump, done around 10 track days and all I've done is change the oil.
I'm not saying a boosted engine can't be good on track, but it requires a lot more work, money and time to get it right.