Matho, this apache 84 with this configuration runs very good, tested 3 times with 2 different radios, tomarrow i'v get my new radio and saturday, if the the weather let me(its too cold here in Italy),  i will do some videos of her in water.
However, your numbers, 30kg, 20 hp are too high <span class="hps">from my humble point</span> <span class="hps">of view,</span> or too professional figures, i don't want an xtreme racing boat, i saw a lot of big apaches on youtube with only one blata 45 cc or rcmk twin cyl 52 cc like mines working with 2 props and a gearbox and runing very well, i think it <span class="hps">depends on the</span> <span class="hps">tastes and</span> <span class="hps">expectations of performance of each</span> <span class="hps">person, i'm sure that your boat is an extreme powerboat, 4 cyl on a reckless... love to see it.</span>