On the exhaust issue, my collector was cut back by the muffler shop and I have no idea how much because they did it without consulting me. I simply told them to put a new exhaust, from the collector back, using 2.5 inch pipe from the collector back to the muffler. To do that, they cut some off the end to get somewhat of an oval that was close to the 2.5 inch pipe, squashed the 2.5 inch pipe and welded it on the collector. Most of the factory collector is there.
I would guess that this is not unusual for those of us that have changed from the stock exhaust. By the way, they did the same thing on the gold car exhaust when they did it last year.
I would hope that this never becomes an issue as both of my exhaust systems were done in the same manner and I would hate to have to throw them out and buy more stuff (low cost racing:) .
Big Dog