mph

has anybody ever upgraded their bird to the point where the factory 120mph speedo doesn't cut it anymore? mine used to and i yanked the powertrain out and replaced them with some out of a 150mph car. i estimate that the additional wieght, wind resistance, and rear gear will probibly drop that to about 135 or 40. is there an upgrade available or another mn12 with more adapt gauges to swap in?, i don't want a big aftermarket piece cluttering my dash up{:-(