I've been trying to find online ( Google ).. Explanation on horsepower/performance and how it works  in a jet boat.. If I have a 386 hp motor and I decide to go with a 450 hp motor.. I'm to believe that, all I gain is quicker out of the hole and maybe a little more top end speed.. That fact is the pump and impeller will still be turning at the same rpms ( may it be 4,000/4,500 rpms ).. What are the benefits for increasing horsepower.. Less strain on motor to achieve rpms?? Please, anyone who can explain.. Thank You     

Thank you, for the reply Mr. Brunt !!  My Marine power 454 (386 hp) motor seized up over the weekend.. I can't explain how/why !! I thought I sucked something up into the pump or rope around the shaft..Motor just died and than noticed motor took on some heat..I had a marina in Laughlin look at it..No water in the oil/all plugs look fine... Yet, the teeth on the starter look rounded on edge and they said they couldn't get the fly wheel to move at all..With that said ( I have seized motor ).. Now, I have the chance to throw in a rebuilt 454 motor 450 hp with upgrades steel rods/steel pistons etc....   I'm not going to lie.. My boat ran awesome for the last 9 years on that motor..I hope I'm doing the right thing..I used to go to Tom Papp for service.. I don't know much about motors and I trusted him..I appreciate any info. and glad I found this website..THANK YOU !!

Thats a nice boat I would make sure that the engine was Seized first for sure if everything looks good oil plugs and the engine just wont crank over may be your pump sezied up not the engine I would disconnect the engine from the Pump and check to see if you can turn the engine over by using a breaker bar and socket on the front bolt of the harmonic balancer. this would truly tell if your engine is sezied  then try turing the pump by hand to see if you could get it to turn might be a little tough to get it turning

FUNNY YOU SAID THAT RIVERMIKEY !!
 Remember the Holiday marina in Laughlin already diagnosed my engine as seized and charged me $100 for the info.. I was emptying my boat ( towable/life vest etc..) When I started looking around at the motor and the pump.. I noticed that the impeller had a slight gap to one side of it.. So, I took the 8 bolts off and discovered when I removed it..Metal chips fell out.. I wiggled the impeller a little and put a wrench on the tension nut.. I could move the shaft.. At this point.. I removed the whole pump and discovered the shaft bearing had broke and caused the impeller to ride into the wear ring. Unbelievable !! First thing I did is cancel Motor from being installed ( definitely didn't make the their day ). Second called laughlin marina and requested my $ back for their diagnosis ( seized engine).
I ordered my bearing, wear ring,impeller and gasket etc.. Once parts get all in.. Have this back together in no time.. Already booked rooms at the river for another week in August.. Motor seems OK.. I am having the starter rebuilt just to clean up a little rounding on the teeth..The teeth on the rotor look fine..I hope I get another 9 years out of this motor.. Somebody up there  likes me  !!  Been a very learning experience.. I've meet a lot of nice folks and thanks for all the words of wisdom.. 

MOST IMPORTANT = I learned the definition of "BOAT"   BRING ON ANOTHER THOUSAND !!

thats good news
come on out to the big river deal at the end of aug

x2