When I did it on my 08 E92 335i I noticed it right away. Might be because I did it in my garage and just wow the roar was so much louder. Almost scared me a bit. I haven't had the chance to drive around with it yet, but the startup sound alone is well worth it for me. Not sure if it effects MPG, but from the sound you think it would.
Originally Posted by xPaulBaiLeyx
Wrong. I just did it to my 2006 330i.
It has it too.
not sure i really noticed any difference at all though. . .
Seemed like nothing changed.
Does it take a while to kick in or should i notice it right away?