I have used and sold SI valves for 15 years. If you spend over a $100 with them (which you will) they make you a dealer. Just give them your last name and add the word Machine to sound like you have a business. They just want to sell valves and since they are in California they shouldn't charge you sales tax either. They are Chinese made, so yes they are a lot cheaper. I know of no one I ever sold valves to that broke one including myself. They are an excellent valve for what you pay, but if your turning the engine over 7500 rpms with a 1000# open spring pressure then I would go with the Ferrea.
