RockShox Vivid 5.1 Setup?

[inshane]

So im currently using a RockShox Vivid 5.1 on my driver 8.
Ive played with the settings myself and tryed the setups suggestions on the rockshox website but im still not satisfied... Id like it to feel like a nice plush dh bike should but the ride just feels harsh. Im 190 pounds and running a 450pound spring. Ive wanted to try a lighter spring but have been told that would be way to light for me.
Few people have told me to play with the air psi but I cant seem to find any articles talking about air setup or settings? Adjusting the psi in the shock would possibly give me a plusher ride?
Could someone please explain and help me with this?
Sorry if I seem brain dead but I get up at 3am every day for work so please be nice.

thanks for ur time!

[JCL]

I think the minimum pressure in the IFP should be 150psi. What compression tune is the shock? You might want to try a lighter tune. When did you last change the oil? That shock is very good. Pisses on the RC4 IMO. In other words it might not be the shock.