the 48v Magic Pie won't go over 500 watt continious power.
so no worries,
they can't properly test the power and if you act nicely you'll have no problems with the police.
also, don't stop pedaling along with the ebike, even if it is only to show your motor only works while pedalling.
I've been pulled over, 250watt is the max here in europe. ALso 25kmh is the max. I've been riding the 48v mp and no pedalling and 45kmh without any consern about beeing pulled over again. They don't know these bikes so well, so make a stickes. Tag it onto your battery, say 24v 500w max etc. just in case