The brembo F50 calipers that are part of the GT kits are wider than the 993 TT calipers, oem pegs will not clear them, you will need at least a 3mm spacer to clear. Also, the pistons are larger, the two smaller ones are 40mm and the two bigger ones are 44, the 993 TT calipers are 36mm and 40mm IIRC They do however work with the IPD brackets and s60 R rotors