ive currently running a fox dhx 4.0 and the 400llb spring is way to stiff for me now looking on tinternet there is a few diffrent lenghts of spring i can choose from is it critical which length i choose

Critical things like your

Weight
Shock length
Amount of rear travel

All determine what spring you need

Check out http://www.tftunedshox.com/info/spring_calculator.aspx look for spring calculator and input the relevant details.

If none of this makes sense then tell us your weight(all kitted up) and bike then we can do it for you.

What shock is it on.I have a few springs.If you want to mail me my addy is in profile.. 😉