Im confused on what to do I have 4.10's and would like to calibrate the speedomiter and tach. Would a tuner like the diablo sport do that or do I need a speedcalibrator? I also am wondering if a tuner would add any horse power to my car? I have a 1996 Gt 5spd. with H-pipe, cat-back, fenderwall intake, plugs and wires, those are the only power adders I have but I also have the 4.10's, King Cobra clutch etc.. Would the tuner be a smart move for me? My car has 118k miles on it but still runs strong.