Gtr Cat On A 3" System?

[Greasy]

Hey guys, iv'e been told that a good (if not better) alternative to a high flow cat is a GTR catalytic converter. I have a 3" turbo back system on my r32 4 dr, will the flanges need to be changed or will it bolt straight up to the system? Also what model GTR cat will be the most suitable r32/33/34?

Any help appreciated. Cheers

[R.3.2.G.T.R]

flange will be the same, i have used a r32 gts-t cat on my GTR without problems.. however still better to get a high flow cat as gtr item will still be 15 odd years old.. metallic over ceramic cat if budget allows