AO Platinum Member
Join Date: Aug 2003
Location: London, England
Re: GT Brake upgrade
Exactly the same as a conversion on a 156/147, you either need to buy a conversion kit which will include radial-mount calipers and separate brackets, or if you use the OEM 305mm Brembos you will also need to purchase & fit the front uprights from a 3.2V6 version of GT/156/147.
As for fitting under your 17" wheels, it depends what 17" wheels you have, some will clear the calipers but some won't.