Originally Posted by 135Pats
So long as you dont touch the primary cats, its extraordinarily rare to have warranty issues with a catback system. It shouldnt be an issue.
I think he is referring to the exhaust itself because it is used. The part comes with a 2 year warranty but you need to call BMW to confirm if the warranty is transferrable. It would also help if you had the original receipt from the seller so you can prove when the part was purchased and that it is within the 2 year period.