hey, i recently swapped a b16 into my 91 rex. i was blessed with the y1 transmission (factory limited slip) however im beginning to hate the fact that i cruise at 70 mph at almost 4500 rpm. its rediculous. since i dont make 5th gear pulls, im considering swapping the 5th with another perhaps USDM 5th to improve gas mileage. i have heard of this being done, searched and found a lot on an '91 LS 5th going into the b16 with the yS1, but nothing on the y1. would this be different. if so, has anyone done this? also, what would you recommend for the 5th gear? the LS? GSR? USDM Si? and how should i buy it? new? junkyard?? i basically clueless (obviously) anyways, any help would be greatly appreciated. thanks a lot guys.