OP - I'm not sure if this will help, but this sounds like a 1 out of 10 (10 being bad) in terms of being screwed by a dishonest E9x seller. So so many more things are 10x worse than essentially test pipes and an OEM mod... to name a few: dumping a rod knocking car, hiding an accident with significant body damage, various oil leaks that could occur, etc.. Selling a car with this MINOR of a list of modifications is pretty much nothing in terms of dumping "cost" onto another owner unexpectedly. If you had a PPI, which any buyer should do, it would have caught this ~$300 fix, and I'm sure you could have shaved it off the purchase easily. I'm kind confused by the entire thing I just read.... you could probably trade a modified x-pipe & modded OEM exhaust for stock and made a few hundred bucks on the deal easily.
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