It is all about compression. I bumped up the compression in my Beemer to 12:1 and now I have to use 103 so she doesn't knock. I always say premium over 10.5:1 or 11:1. I could be wrong but that is what I have heard. I used to always run C10 in my car when ever I could, and I could bump my boost up to around 20psi and not worry.
Last edited by 1percenter; 10-19-2005 at 09:17 AM.