Its the other way around. the purpose of the P-valve is to balance the braking force between the frt and the rear brakes...more specifically, the piston sizes used provided the BBK are the same brand frt and rear. The P-valve should have clearly defined positions(Tilton) not infinite adjustable(Russell) so you know where your sweet spot is.
If you have BBK and the frt & rear have the same piston size for economic reason, you would/should need a P-valve to balance the brake, but then again, depending on your driving preference or how much you are willing to adapt.
ie. I have oem brakes with the ABS delete since 08, the frt caliper pistons is bigger than the rear so I am ok on the road and on the track. Stop Tech, AFAIK, use different size pistons so they can say its "made for the NSX". Its all physics of Force = P/A (pressure over area).
If you have BBK and the calipers are the same frt and rear, w/o the P-valve under heavy braking, the rear may lock up due to weight transfer and you might find yourself facing the wrong way....not saying this will happen but depending on your driving skills.
IMO, ABS 1.0 is designed in the later '80s so this solution makes more sense than the 02 ABS upgrade designed in the mid '90s where you spend $2k+, special JDM NSX-R s/w? a minimum of a whole day of labor for installation + bleeding, saving 15lbs, and its only better than the ABS 1.0 and that is not saying a lot AND to activate it, you have to brake like mad which you should not do on the road or on the track(no purse for winning or looking for that 1/10th Hero of the day risking going off track
) especially if your treadwear rating is not around 100 or lower. If its raining, slow way down and hope the yahoo next to you pays attention. If we spend over $2k on a mod, we should use it or have it work for us as often as it can to maximize the benefits.
After we release the prepreg frt bumper next week, we'll be revisit the P-valve solution so should have new parts before Thxgiving. Too much to do and too little time but we'll get there.