Exhaust question again.

Hi all, sorry about this but I have been reading and researching for hours now and need some help/advise.
I have a 2002 cooper S which has lots of mods already including a GTT re route pipe and there slash cut tips. Sounds good.
My question is should I go for MILLTEK cat back exhaust or GTT SPORTS MANIFOLD C/W REMOVABLE CAT SECTION?