do performance valve springs add hp or do they just raise rpm's?

 

They won't raise your rpms but perform better at higher rpms. You wont see and hp increase either. They may be a bit lighter than stock.....but thats about it.

 

high performance valve springs are part of a whole package that you should do all together. if you replace the valves, springs, and retainers, then yes, it will raise your redline( I assume thats what you meant by rpms) and in itself, you will see marginal or no hp gains, as the stock cams will choke out the motor at higher-than-stock RPMs. the power is found in high performance cams, hi-po valves, springs, and retainers, along with a computer mod that will allow you to move your rev limiter up to utilize the bigger cams. the springs are a means of making more power, not a power mod in themselves.