23cc with twin yamaha f150's, numbers???

[23acrplanes]

I have had twins on my 1984 23cc for about 6 months now and I'm still playing with props and motor height. Has anyone on here already done this and can tell me the best setup?? And I don't have bracket.

As of now my numbers are

4000rpm 30 mph
4400rpm 33 mph

I get 6100 rpm but then I get a speed wobble and have to pull it back, so I don't ever get a chance to see the top speed.