Custom built injector based on vehicle specifics and intended use. Recommended for 625+ RWHP applications & P-Pump conversion. No core charge. Injectors are intended for high performance and competition use only. No towing due to excessive EGT's. Included with these injectors are new injector O-Rings as well as new copper washers. With so many manufacturers making 24 valve injectors, how do you choose which one is right for you? DDP injectors are not the cheapest or the most expensive, but they are guaranteed to be the best. Which is why these injectors come with a 1-year unlimited mile warranty.