All,
My first post here, please be gentle with me.
I'm considering purchasing a 2003 Mustang GT from a local dealer (finally!! I've been drooling over Mustangs for too long, and my wife for even longer), and took it to a local mechanic that I've developed some trust in to look it over. He said (and here I'm paraphrasing, probably not perfectly,) that the front half of the exhaust system isn't factory, and isn't a kit - someone did a bit of hacking in welding in different parts. He can't tell if the catalytic converters are the correct model, the O2 sensors appear to have been added ad hoc, there's no longer a central connect between the two sides of the system, flanges have been replaced with welded connections (and the pipes used were of a slightly different diameter so there's a bit more weld than would ordinarily be necessary), and the right muffler was at some point rubbing on the drive shaft and is still a bit too close to it. The mechanic says that he's not sure if it'll pass an emissions test, and the Check Engine light will probably light up soon. Replacement of the front section of the exhaust is estimated at $1800, with a couple hundred more refitting the back end.
The dealership manager pooh-poohs the $1800 figure after taking the car to their shop, and says $700 to do it. I've told them that if they can do it that much more cheaply, that they might as well go ahead and do it themselves and then we'll get down to negotiating the price (he didn't seem to like that idea much), but given the circumstances I was wondering if some folks that know what they're talking about and don't have any stake in this could help me out. Any advice you could give me would be appreciated.
2003 Mustang GT purchase, exhaust system replacement cost? 
