Ok i was talking to the guy at jackson racing and he said to determine the amount of boost ill get with a 3 in pulley i have to figure out how big or small the d16y5 crank is what its mesurements are to the d16a6 weather its bigger or smaler than the stock one on a 88-91 civic si model so if anyoen could tell me what size the d16y5 crank pulley s cpmpared to the si motor crank. i really need some help on this so if someone knows what model has the smallest crank let me know i dont want to run that much boost and if the d16y5 is bigger than the 88-91 si model i will be boosting way to much.