I replaced my crossover and under battery pipe on the standard tune and my boost readings didnt change at all... I dont think they are worth the effort long 2.25" pipe runs and a restrictive cooler are the problems, so if your retaining the factory pipes, I would leave the crossover as is.... even though it flattens out, it doesnt reduce area.... and even though the UBP changes shape, it also doesnt reduce(I cut it open an measured it) so nothing really to be gained there either.... hope that helps