Originally Posted by 07bmw335iguy
Ok I gotcha, I always thought the tuners manipulated the computer somehow, didnt realize all they did was keep the cel from coming on. Looks like I'm going to go ahead and install my dp's early then
They do. Poster above is incorrect. And as per Terry it's better to Remove the down pipe fix rather than to just leave it in as the Jb4 does a better job. The dpfix is usually just for inspection with jb4 disabled and should be removed after.