i thought that the VX grears are longer than the Si, the VX was for eco and the Si was for sporty kind of deal, and if u want a VX trany under a built motor in my mind u just wasted ur time, thats likt takeing a fully built GSR and throwing a ls tranny on it to me, it will take u for ever to get up to speed and would suck ass if ur in a race cuz u wont keep up