All K-series engines. K-Tuned is now offering sets of OEM (Denso) Acura RDX injectors. These injectors are rated for 410cc (at 38 psi) and 550cc (at 70psi) and offer a much improved spray pattern over the factory Type-S (310 cc) injectors. These features offer the K-series engine increased fuel flow and better fuel atomization. They are the perfect upgrade for stock and modified N/A K-series engines. Stock bottom end motors with cams, valvetrain and upgraded intake manifolds may already be maxing out the duty cycle of the factory Type-S injectors. Please note that Kpro or other engine management is essential to control these higher flowing injectors.You can choose to buy a set of 4 injectors only or buy them as a combo kit with injectors and pigtail clips. We are also selling the pigtail clips for people who just need them.