I dont know weather its the midpipe but i have noticed that if i even tap the pedal or hold slight pressure on the pedal that my revs speed up very quickly to like 4000 with little effort of the gas pedal and that the speedometer reads like 20kilometers this is in 3rd gear! could it be the midpipe because now there is now back pressure and the engine can breath and dump its exhaust gases more easily? I dont know what do you guys think?

 

Slipping clutch?

 

It's probably your clutch, do you ever smell anything burning when you rev high in gear? Clutch smoke is kinda spicy smelling... I still have nightmares about a friend of mine burning the crap out of my old Talon's clutch once. :P I've got a full straight thru exhaust on my FD, and it revs cleanly but not as high at low speeds as yours, that's not normal.