i can put 1000cc injectors on my d15b7 and run it all day long. it will have amazing throttle responce, but it will change verry little.reasonably 550cc inje tors are fine. 750 for upgrades later or running more psi. use the calculator i posted earlier. and it will tell you what you need. it will give it to you in terms of power goals, but if your only looking for 220 or so, then 550 will be fine.