How does a stock impeller for a Yamaha VX110 work for pitch? According to my service manual it shows a pitch of 21.2. Thats it. Does that mean it's a straight pitch? Or always working at that number?

I purchased a Solas 18/24 for my VX. After installed by my dealer, I tested the ski and the performance feels not to par. Top speed is about the same, but the bottom end and midrange is not really that great. The ski feels less responsive or heavier. Doesn't seem to be cavatating.

My point is, if the stock is straight pitched 21.2, wouldn't the variable 18/24 give me pretty quick bottom end and the 24 give some better top speed?