Hey guys like i said i have a b18b1 swaped em1, its turbo why i swaped to the ls plus the b16 in the car was junk. but back on track, its a stock ls motor and trans and i believe its a modded ls ecu with an s300 in it. Now my speedo is off by allmost 10 mph at times. At lower speeds its like 5-7 mph but once im around 30+ its about 10mph off. Just wondering if any one had this problem befour. Also it has stock si wheels and 195/50/15's on it if that helps.