[FranzX3M]

I installed the Ultimate Racing catted downpipe. I had a performance muffler shop install it and it was pretty easy with a lift. I also installed a new front clamp and gasket from BMW. Review: SOUND. Wow I was expecting some change but was impressed with how much more exhaust sound there is using this with the stock M exhaust. Its louder and similar to adding a performance exhaust. I was considering doing the exhaust but this alone is enough.Goes to show how restrictive the stock cat is. Performance, it does help bring the boost on sooner and a bit more top end. Ultimate says 15 hp but can't verify. It is made of SS and has metallic race cat. Now they say some cars will throw a code and some won't, mine did for cat efficiency but it does not affect performance. I am going to get a performance tune that will remove the code as well. They also sell a cat-less version that is even cheaper.