at present i m running a 1835, with a standard box , had it rolling roaded giving me 100bhp at wheels . problem ive got is my speedo is allover the place , reads whatever it wants ive put nes set of clocks in , no better, can i guage my speed off my sat nav and what should i comfertably be able to cruise at , this is in a tintop with devon interior ,thanks in advance