when buying a fuel pump you want one that will do a little more than needed as a margin of safety. i dont know about your setup, what your fuel requirements will be, what your applicaiton is, etc. But, I know that Walbro makes standard and high pressure pumps. Since your going to be going with larger injectors and the afc you will obviously have a higher flow requirement. Due to this you will want to go with the high pressure because it is more likely to be able to keep up with the new requirements than the standard one. So go with the high pressure.