I've read that the Hi-Power model has a max of 155mph (limited) and 0-60 of 6secs (not sure if this is all accurate), was wondering if anyone know what the corresponding Low-Power figures are?

MAzda have not yet released 'official' figure as far as I know (even their press release does not give any - or fuel consumption figures for that matter)

General magazine reviews seem to pitch at
0-60 in ~6.0 for High power and ~7.5 for Low power
Top speed 150MPH for High power and ~135 for Low power.

I think the term 'Low power' is a little harsh.
I mean , it is still knocking on 200bhp and will see off most hot hatches on the road ! Maybe they should have done a McDonalds and had 'Regular and High power' :)