spAdam

iTrader: (1)

Where does that put you, compression wise? I'm thinking right around 11.5:1 for PR3s. I think that would be fine on 93, maybe a little knocky from time to time on 91 though. Nothing a mild cam with a little overlap wouldn't fix. A P73-A0 piston would put you just north of 11:1, which would run just fine on premium fuel and a stock ecu.

KPDSM

I think its right around 11.2/11.3
When I put this together I'll make sure to use premium and an octane booster, even when/if I cam it.
P73's require machining to the pr4 rod - which I don't know if my machine shop has experience with on Hondas.
I actually already have pr3 pistons on pr4 rods sitting in my garage.

(not so) funny story - I got the piston/rods put together before I got the engine back from machine shop that they were going in. I went to install pistons after the crank and my ring clearances weren't even close. 3 beers and about 40 minutes of staring at it made me check one of the pistons that came OUT of the engine before it went to machine shop.
They were stamped .050, but because the engine had been sitting (bought off offerup) and there was water as well as carbon on top of the pistons, I never saw it upon disassembly.