Ive looked at bringing in exhaust's and after lengthy conversations this is why Im saying it, for the extreme cost of bringing one in, a well made custom system will be just as good if not better, granted there are some terrible custom exhausts out there, my first longlife one for an example...
But from somewhere like AAS or MIJ with good mandrel bends and decent construction theres no need to fork out £500+ on a brand name one.
but this is just my opinion from my own inquiries.. if there are so good howcome theres been a 5zigen system on ebay for over a week at around £200 delivered?