Hello,
Welcome to the forum.
A remap is a must for any GTI.
A Revo remap running 250bhp on your 2005 GTI is a good and safe option and should not cause any damage to your engine.
You engine set up is good for 300bhp+, The only thing limiting you to going to 300bhp+ is the stock fuel pump.
We are pushing the 197bhp 2.0tfsi to 250bhp+ with out any issues at all, EGTs are still very low, same with the 1.8t we tune some are running over 70bhp over stock and being driven every day some have 150+k on the clocks.
The horror stories which have dogged the chipping and remapping game come drivers who dont know how to care for there cars, running low oil and thrashing the car, not letting the turbo spool down and cool down before turning the engine off, cheap cone filters, constant redline driving, driving with faults stored in the ecu, cheap and nasty BOVs relocated elsewhere, MBCs added.... poor servicing ...the list will go on.
If you have a good nose in the MK5 section I am 100% sure the guys in there will put you right and tell you the ins and outs.
If you approach Revo with your concerns I am sure they will put your mind at ease aswell.
Nick
R-Tech