teach me on AFR

Well it's impossible to say what is the best because every car runs slightly different. GENERALLY though,on a naturally aspirated vehicle,anywhere from 12.5 to as high as 13.5 is ideal. You won't know whats best until you can get it on a dyno and check it. Easiest way to adjust it is with any of the handheld programmers,of which SCT and Predator are common but there's a few others out there too. As for brand of FPR,BBK makes excellent stuff but PP seems to be a great bang for the buck.