It depends on the FMF Pipe you have. Currently they have a "Fatty" which is no longer produced, they have a Gnarly (torque), and now a Gnarly Desert (replaces the Fatty) which has huge amounts of top-end gain and the expense of some lower grunt. I ride FMF on every single bike I've got in the dirt and I ride all wide open, not very much grunting so the FMF Fatty or Desert Rev are my choices. I don't know all that much about ProCircut.