Sure, good question.
1) I purchased a new exhaust for my 2001 and the aftermarket catalytic converter had an incorrect jig. It was a headache. In the end I purchased from Mitsu.. I'm not a mechanic by any means, but it still sucked waiting, returning etc. I have not patience.
2) My mechanic who can or knows people who can perform anything related to cars, told me to buy a fitted system. It's to hard to make the bends fit with accuracy.

That said, your point is made and I'll look into it for the pipes out of the manifold.
Thanks,
Brian <img src="/forums/images/graemlins/kewl.gif" alt="" />