Ok, I have to disagree with this post at least part of it anyway.
" During the Burnout and Staging the Power Valve will likely remain shut and the Carb will only be receiving fuel from the Main Jets which are smaller ( than when run w/o a PV ) so it will be running leaner "
Durning the burnout at least mine anyway I'm almost always have the throttle at wide open or pretty close to it which would mean there is zero manifold vacuum and any power valve if installed would be open not closed since vacuum holds a PV closed not open.
Now I agree in staging it should be closed but this is where I get concerned with running a PV especially when "STAGGED", if you foot brake like I do while your torquing up the motor while STAGGED there is a chance that engine vacuum can drop enough to let the PV open or start to open which can cause a part throttle rich condition. Some people run a PV with a lower rating to try and combat this but this is primarily the reason I dont run one. Why take a chance on having a stumble or monkeying with my ET consistency?
Now if you run a box class you'll have it hammer down when stagged so it wont matter then.
JMO> Charles