[Dimis]

Hi guys I am looking into upgrading my M2 with a sport Cat and a piggy back ECU, does anyone know if replacing the original Cat with a free flowing sport Cat will have any adverse impact on the car considering it will also have a piggy back ECU designed to work with the OEM cat ?

To give a few more details I am looking into the Lightweight HJS 300 Sport Cat which I have heard good stuff about and also looking into the AC Schnitzer ECU performance upgrade (mostly because of the warranty, I know its very expensive and not a lot of gains max 50 hp however I do trust them as a company meaning no engine lights, issues that I have heard off etc) however when I called AC and asked them if there will be any issues using their performance upgrade together with a sport cat they didn't know and they did mention that if something goes wrong with the engine the fact that I would have a sport cat might invalidate their warranty.

I am no engineer however from the little I know I cant see how a sport cat would have an adverse impact on the engine if used in combination with an ECU piggy back. Can someone with more technical knowledge chip in ?