The spring will make no differance to power you can, You can use the green spring of you want, as the top boost feed will keep the dv fully shut under load.
The yellow spring is used to get a crisper lift of and make part throttle spool up driving much better, part throttle with vary the maifold pressure which under higher part throttle load can cause the DV to flutter open a bit, having the added spring pre load will make the varying maifold pressure realted dv isues less sensitive. Its got nothing to do with what WOT boost the DV can hold as there is no pressure acting on the pistion or spring..
I am running 24psi peak and 21psi at 6000rpm and only using green springs... albeit with two Forge 007p DVs in line..lol