Pawel - it depends on several parameters really - how light do you build? how profecient a pilot are you? etc.

I finished mine weighing exactly within the range written on the kit box, and I had the engine on hand.
It is a very powerful combo, when I climb for a stall turn for example I usually close the throttle in order not to go too high (and then open momentarily to kick the tail around).

I takeoff on full power and close the throttle immediately after the initial climb out, and rarely see more than 75% throttle during the rest of the flight.

It also depends on your style of flying (I like to fly rather relaxed - you land in the same place anyway so why fly fast? ) and does your flying field have any special limitations or obstacles - like trees that need to be climbed over quickly etc. (my field is a real airplane landing strip - no limits around).

But in the end - it's your decision.