The SX is very durable and comparable to bravo, heads and shoulders above Alpha. The SX upper is same as the DP Volvo and they used them on 496 I believe. I have a much lower HP SBC and a SX drive. however I d o a ton of wake boarding and am very hard on drives. (in and out gear, full throttle starts etc......tore an alpha up about every 2 years). The main thought on drives is you can treat them right and they will live a long time . or you can break them pretty quickly too if you try.