CTR N1 also has timing marks. So does my UR pulley. Most REAL aftermarket pulley's have timing marks. Ebay pulleys don't, but you can put your own on them. Underdrive pulley's have been around for about as long as street racing has. Old american cars have used them for years and never had a problem. And they are actually replacing their harmonic dampers with steel underdrive pulleys. It's a garenteed way to increase wheel hp.