I think cai on forced induction is a waste of time, any lower temps will be nullified as soon as the air passes through the hot turbo. For lower intake temps you need to upgrade that tiny intercooler the gtis have. IMO you won't see much, if any power increase on an un-chipped gti with an intake upgrade, I barely noticed mine even with a chip, awsome sound though. There is a reason why everyone recommends a chip as the first mod to a Mk4 gti....