I have dropped in a set from Five-O motorsports, called Black-ops rated at 550cc's. There is a plastic adapter available so that there should be no need to cut and solder electrical connectors, however, on our engine there is not enough clearance, cut and solder it is. When comparing injectors it is important to make sure the stated flow rates are at the same pressure, most use 3 bar as a reference. While some of us using stacked set ups have adjusted the fuel pressure to about 66psi, after installing the Black-ops injectors, I am going to go back to the stock 58 psi. Five-O motorsports can provide a lot of good info on injectors, plus the injectors came with a flow sheet showing all 6 injectors and their flow matched to very close tolerances and the rate at different psi's.