**** dude then try it

The stock ecu map goes up to 125% calculated load, that should be more than enough to handle that little amount of boost.
Again back to the flow map of the compressor, as it may not actually be able to make any boost on the 8 but what the hell.
The stock tune can IMO absolutely handle 1psi without any tuning.
Saying that tho ... I don't like the stock tuning on the RX8 anyway ... way too rich

 

BUT : the max calc load map wont allow 125% (forgetting about the baro and temp modifiers) .
In actuality you would get away with 1 psi but only because it runs rich to start with.

 

I do have an AP that I can fine tune everything once its installed. Honestly I only think that it'll make up for the low compression the 8 is notorious for. I had mine compression tested last week and it rated minimum on mazdas scale. all rotor faces scored in the lower 6.3-.6.1(kpa) range at 222rpm on front and 203rpm on rear at normal operating temp. Engine has 62k miles.

 

All you need do is increase the settings on the 'max. calc load ' map by about 15% and that will take care of it up to 2 psi.