Cam gears DON'T advance or retard timing. They adjust the cam timing or more specifically when the intake and exhaust valve open or close in relation to cylinder compression, FYI.:doh: I would stay away from HKS gears. They seem to have a tendency to chew up timing belts. Titan has a nice set that are 5 bolt that are very secure. As for pulleys, Orthodox and Greddy both have sets that are decent. Stay away from the eBay stuff and don't use an underdrive crank pulley. They are not dampened so they don't absorb any driveline shock or abnormalities. Underdrive pulley are just smaller or larger than stock depending on that they are turning. A larger pulley will make something turn slower, a smaller one will turn faster. Get a Boostlogic crank pulley if you are replacing it. It's dampened and well made. Comes in black and silver.