NY state lemon law, buyer's rights under NY state law for used car purchase and sale

Most sales in NY are "as is" unless there is a written warranty or the Lemon Law applies.Since it was not bought from a dealer, NY's "caveat emptor" law would apply. That means "let the buyer beware" Inspecting the car after you purchased it does not help your situation. The problem you will have is proving the statement that the seller gave about the muffler system. He is likely to deny ever saying that if you try to sue him for fraud. It will likely cost you less to fix the muffler system than it will to try and hire a lawyer to sue them for fraud anyway. You can sue them without a lawyer in small claims court, but with the facts you present here, I don't think you will win.