Originally Posted by AKSubieDubie
I can see that. I remember reading on a thread about the same theory. I played with it a bunch and didn't really see any difference in learned knock values.
I think I'll be zero-ing them out when I finally build a set of equal length headers, as my current tune seems to be spot on with timing. Been ripping around with the 30r maxxed out for about 20k miles! (motor has 24k on it since rebuild)
Just something to think about.
I would not zero them out, if you coming within 1-3 degrees of knock you should be adjusting your timing for that load/rpm range. Even forged pistons can break with knock or at least rip up your rod bearings. I don't think this theory about exhaust making a difference makes an sense. More or less spark timing within a few degrees all happens with the exhaust and intake valves shut. Regardless I doubt any real gains are here plus on your car were talking about 1-3 degrees between just 5200-6400 rpm. Tiny window...