If you have a kit it should give spects in the kit,,if in dought set with gskt on as that will lower fuel level in carb the thickness of the gskt and that will cause the engine to run a touch leaner and in most cases that is good,,but in some cases if the engine is on the lean edge it gould cause you to use too much throttle at crusing speed thus opening the power sys to early and fuel milage giong down..OH God I,m rambling agin sorry...doc