You can only install them "straight up" with the stock gears. There is no provision for advancing or retarding with them. They work fine that way, but if you really want to play with your car on a dyno, you can buy a set of adjustable cam gears now and play with them to your hearts content! There is supposed to be a bit more power with one slightly retarded and one slightly advanced but I can't remember which. It's not a huge amount. The adjustables mainly shift the power to a different point in the rpm range.