As above... I currently have the Milltek Evo mani and a Piper cat back to a standard Cat which obviously will fit but I'm currently trying to find out weather the Milltek sports cat would bridge the gap.
i had a piper manifold with blueflame exhaust and sports cat
i think most manifolds will fit to the original cat and all exhausts with sports cat / decat fit to the original flexi
i wouldnt of thought it would be that much of a problem
the main thing as already said is the bore size
Milltek and Piper Manifolds attach in the same way as a standard manifold, So you could have a Piper manifold with a Miltek full exhaust or a standard exhaust.
Piper and Miltek Sports cats/decats are different lengths and bore sizes (ID: 55 Piper, 57Miltek), so will ONLY fit there own Catback. But as said above a Piper sportscat and catback can fit onto a Miltek Manifold fine, or vice versa.
Mountune Catback center piper (S pipe) is MUCH shorter than Milteks or Pipers so will not fit either system.
Im not 100% sure on:
Mongoose generally have a solid Manifold without a flexi, unlike all the others. The flexi pipe section is attached to the Sportscat or decat. Mongoose catbacks i *THINK* are the same length as the Mountune one, so i think a Mongoose manifold and sports cat will fit a Mountune catback. Dont quote me on this though.