I have a superchip, K & N air intake and banks catback exaust in my 6. The superchip has a choice for high octane fuel or regular and I set it to high and run premium. (not a dailey driver) I think my jeep runs great and maybe that is partly due to the combo of these upgrades, but all these items advertise BIG HP gains and they dont come even close to delivering. Total investment per HP would be very dissapointing. About $1200. Small engine manufacturing were involved in a lawsuit about how they rated HP on lawnmowers etc and it was determined that the HP they advertised was peak (just before the engine blew) They lost and now most advertise torque ratings.