The Hamilton units are rated up to 2900 RPM idoes your gearbox have any reduction or have you had any bearing work done.
I am not sure, will find out for you.
Also when you whipped the Cat out and put an Iveco in I presume the toobs rose out of the wqater a bit has this affected the high speed turning at all. Did you gain speed or lose it with the replacemant engine
Being a 4 ton boat it didnt make a noticable difference with tube hight out of the water, Tubes sit above the waterline anyway...just.
The boat turns alot sharper than she used to, especially to Starboard. Ride is also softer and easier.
Speed wise we lost three knots after we had played around with impelles and gearboxes etc, unsure what affected and were, mainly because i cant remember lol.
Will dig a little deeper and find out for you.