I'm prettt sure the Mk7.5 GTI Performance has same size brake discs but aren't cross drilled like the TCR and a clubsport. On the road frankly won't make a difference but I didn't buy a GTI Performance so don't want to downgrade it even if it would save some money! I'm pretty sure I won't need to change the discs for a while longer anyway 
Iirc, GTIP discs are 330mm and CSS/TCR discs are 340mm.
I'm not sure that's right. The GTIP and the CSS/TCR discs are the same size, pads size too, the VW cost cutting led to just putting different discs and pad compound of the CSS, the TCR has the exact same part number as the GTIP for pads, so only got the discs. If my memory serves my right from the VIN and part number look ups I did.