problem is the hole to the oil filter tapers down to less then 0.5in. so theres your restriction. i plugged that hole wit ha 1/2in press in pipe plug. the hole below it which is used for the oil cooler feed on n/a's, is directly from the pump. i intend to drill and tap that for a 20mm to 10an fitting. and the passage to that from the pump and the pump outlet im doing the same, and runing a 10an line from the pump to that fitting. then a 10an into the block. all my oil lines will be 10 an. i figure since this will be transfered to my race motor when done might as well just go all out on it. 8an should be fine, but i figure 10an cant possibly hurt.