Well thats the thing, the heads are brand new rebuilt 973 heads. New valves, retainers, seats AND springs. As for what springs are on there?? idk but they have Zero miles on them. And since everyone is telling me to use stock 340 springs do I really need to change my new stock springs? Id just hate to waste new parts if i don't need to. Plus the few bucks to get em installed. Thanks for the links and info on the other springs tho, i definitely wasn't looking hard enough...then again i didn't know 340 springs were different / better than stock 318 springs