I have no b4 and after to qualify any gains. My combination seams to be working pretty well though. What I can say is they are very high quality pieces and will give the intake a howl that'll give you wood. Based on my experience and what I've learned (and read) I would on suggest them if you are going to get a full system and custom map. If I had it to do again, I would not have bought them unless i was getting the full system and custom at the same time.