I have a 2007 Yamaha F115 on a 2007 Duckworth Advantage Classic 19.5'. My current prop is a 13x19, at WOT I'm hitting about 6300 rpm. My range is 5000-6000 rpm. On a whim I bought a stainless 13x21 but have not tried it yet. Was looking for opinions on how the 13x21 ss will perform on this...