Fuel Systems When modifying your vehicle the most important thing is to make sure you've got enough fuel to handle the power you'd like to make. The first step would be to figure out what power level you're looking to support. From that you can choose the appropriate system. We offer fuel system upgrades starting from a simple line upgrade all the way up to 1200rwhp complete systems. Making sure to pick the correct injector size is also very important. You want to choose the injector that best fits the HP level you're looking to support. Going with too large of an injector may be harder for your tuner to tune and may also sacrifice adjustability. 39lb injectors are typically good until the 550rwhp range. 63lb injectors are great for 550-725rwgp. 80's are for cars making 700-900rwhp. 105's are great for 800-1200rwhp and the 205's are good for 1100-1700rwhp.