Basic Kit for Improving the Performance of GX390s, 420 Predators, 13/15 HP Chinese OHVs. Simple to Install and Provides Significant Performance Increases!

A Step up from the Stage 1, This Kit Is Designed to Improve the Power and Durability of GX340s and GX390s.

Now You Are Getting Serious! A Step up from Our Stage 2 Kit, This Will Further Empower the 420, Producing up to 20+ HP.

As step up from the Stage 1, this kit is designed to improve the power for the GX340s and GX390s along with improving the durability.

The Stage 4 kit starts with package similar to that of the stage 3 but adds a Ported and Milled Head with stainless, stainless valves, stud kit, & HD valve train components. This kits allows up to 35+ HP out of a GX390 and 40+ out of 420/440cc engines.

The Stage 4 kit starts with package similar to that of the stage 3 but adds a Ported and Milled Head with stainless, stainless valves, stud kit, & HD valve train components. This kits allows up to 35+ HP out of a GX390 and 40+ out of 420/440cc engines.

The Stage 4 kit starts with package similar to that of the stage 3 but adds a Ported and Milled Head with stainless, stainless valves, stud kit, & HD valve train components. This kits allows up to 35+ HP out of a GX390 and 40+ out of 420/440cc engines.