I have the Mac high flow cat system with Flowmaster cat back system on my 93 Mustang. The beauty of the Mac system is you can unbolt the cat H-pipe and put in an offroad H-pipe right? My system has 2 hangers welded to the Cat part of the system. Mac Tech's told me that is the old system. The hangers are on the long tubes now, connected to the stock headers. I just want to be able to swap out the Cats to the off road when I have to take a sniff test. I think I have to buy a whole new Off road system to get the hangers in the right place. And if I do i'll just cut the hangers off the Cat H-pipe of the old, I just hope they will bolt right up again when I want to change back. Any Help

 

I've never tried to swap between the two before....you just need to compare them to see if they will fit but I don't believe the 2 systems are identical.

 

I posted a reply to your muffler thread but I'm confused here; do you have longtube headers or stock shorty style headers? If you have shorty style headers you need a midpipe that will be equal to the stock midpipe length. If you have long tube headers you need a short mid-pipe section. I can't imagine why a catted mid-pipe would be a different length than an off road pipe made for the same style headers, maybe I'm missing something though.

Heres a pic of my BBK shorties next to the stock headers: http://rides.webshots.com/photo/2937...79103454trTcdT

and heres the Mac 3-piece off road H pipe next to the stock h-pipe: http://rides.webshots.com/photo/2443...79103454AudgGt

Both after market pieces were the same length as the stock pieces they replaced, I suppose there could be a slight difference in length but everything bolted together.
My Mac h-pipe also had hangers on it but there was no where on the car to connect them. I cut them off, but I kinda wished I would have left them on there if I ever was ambitious enough to try to connect them somehow.