I'm running a 2005 250 HPDI on my boat, and a lot of times in the summer I run on waters with a 45 mph speed limit. I'm currently running a 27 T1 and a 27 VMX. My boat performs very well with these props on big unlimited speed waters, but on the 45 mph lakes I reach the speed limit at about 3500 RPM. Would it be wise to run a 25 pitch on the smaller waters? I'm wondering if running at low rpm's for extended times will be hard on my engine?