Welcome!
I never like to go too hot on P90s as they get too muddy and fizzy.
Depending on how much dirt your amp/pedals have, I'd go with a regular P90 if you've got a highish gain setup. You can pile on the overdrive then. If you're using a vintage toned rig and want to go straight into the amp, or use a light boost, I'd got with a P91.
I've only ever used P90s, so maybe someone with a P91 (PhillyQ or Hunter?) will chime in here :)