The xev cam needs retarding half a tooth which means to fit it you need to modify your pulley or buy an adjustable one. The regal cam drops straight in. The regal cam has more lift than the xev cam so in theory should produce more torque. The only before and after figures I ever found showed a peak increase of 11lbft and 2hp for the XEV, with the eds cam i’ve seen independent figures around +35lbft and +15hp. Ofcourse figures are mapped to suit hardware.