I tried forge 18 psi actuators with both the 530's and gt28r's and it seems the max boost is limited in the 23 - 24 psi range. At first i thought it was a actuator issue but its not. Thats all they will make even with the w/g hose disconnected :) GT28 RS is a different matter - i hve hit 28 psi with those but noticed that there is not a huge power increase between 25 and 28 psi.
Hope this helps
Harry
Formerly yellowzxtt
" If it doesn't make it faster, i don't care " Please visit www.ztuner.com to GO FASTER