I read this article about the 4.0 L engine in a jeep wrangler in last months issue of four wheeler magazine. It talked about putting on a header, cold air intake and a throttle body spacer. Before they installed these parts they dynoed the jeep and it hit 126.4 hp @ 4,474 rpms. They put a lift and tires on which decreased the hp and then put a header on. Now it ran at 128.6 hp. They next put on a airaid cold air intake and a throttle body spacer on. The amount of improvement gained from these two was very suprising to me. It added 25.9 hp to the jeep.

My question is about the tb spacer. So it says that because of the rifling, if you will, ingraved in the tb spacer the velocity of the air is increased increasing the air flow to be combusted. I have heard that a tb spacer doesnt do as much as it says it will do to increase your performance, but my question is this. Will the tb spacer be more effective with a cold air intake because of the increased air flow that the cold air intake gives you over the stock air box? Is this why there was such an increase in this test on the wrangler?