I have a 2002 GTP, 40 anniversary 85,000 miles cat back stock exhaust.This is what Im adding, JMB intake,catless down pipe,PCM, Autolite 104 Plugs, 3.5 pulley. The catless down pipe I assume there are two 02 sensors ? and I would need the down pipe to have the forward bung for 02 and delete the later one ? The PCM I assume I want stock egr,stock evap,stock gears. What do these engines like in the custom tune or standard ? random missfire stock or disable ? timing stock or + 3 degrees ? Thank you for your time.