Ok, I've been reading this info, and as my car has a mostly stock 16v (just a header), I'd like to experiment with a simple version of this. From what I read, a stock engine should stay close to an ideal AFR through the higher RPM with the simple potentiometer/relay system connected to WOT and coolant temp sensors, right? I'd like to make the module "transparent" in the lower RPMs though so it doesn't over-enrich and bog down. So how would I make such a thing kick in with extra ECT resistance at a selected rpm value, say 4000 rpms?