1. How do you know what valve springs to get for stock, mild, high lift and duration cams? I was thinking of spring pressures, spring hieght, and stuff like that.
2. how do you know when to go to a solid cam versus hydrolic. doesn't rpm have something to do with it?
3. when do you need to start using guide plates and hardened pushrods?
I think that'll do for now,(my head is smoking) just thinking again. :D

1. Look at the cam manufacturers specifications.
2. A solid allows a more aggresive ramp, leading to more area under the curve, leading to more torque production. The higher the torque curve is pushed, the more high rpm HP the motor will make.
3. Almost always with a non factory cam. Inreased lift and spring pressure, leads to noodley pushrods, which leads to broken pushrods.