I bought the Group N OMP exhaust for my mk2 and.............
It didnt fit :-( Mounting point changed between mk1 and mk2. Build quality was second to none though (remember its only mild steel), in the end I sent it back as it was going to be too much mither to "adjust" to fit.
ALSO the method OMP use for connecting exhuast sections is sh*te! they dont collar it, they use a stupid spring tensioning system :-( so beware and if you do get it take it to an experienced fitter and pay close attention to how theyre working on it - its fiddly getting it right.......... (I know from another car)
Happy exhaust hunting