crossover or x-pipe

NASCAR guys saw power increases and some new cars run X pipes in their offroad systems. We saw improvements and we saw sound reductions with the X. We ONLY used the original Dr. Gas set up. Can't comment on other's power output changes other that I can tell you some are made incorrectly and some are just wrong. Each car will act differently but they will change the tone (the X) and they will make it harder to remove transmissions.
Tom