What RPM can the 575sci lower end safely take in top end bursts? Im not talking holding it WFO for miles on end...just makeing short top end runs like we all do.

The rev limiter will kick in at 5300-5400 unless you've modifie dteh computer. No reason to spin it faster without major mods.

Aware of the rev limiter...most likely changing heads/cam and would like to know what the bottom can handle. I have also read you do not want to bounce MEFI3 off the limiter so it is going to get bumped up for that reason also.

JRider, what are you running for a prop and drive? have you ran a 5 blade on your boat? what kind of speeds are you getting with the 575sc? I have the same boat, just wondering how others are running.
thanks
larry

Rev limiter cuts fuel, and therefore will melt a piston if you constantly abuse it. Stock limiter is a t 5400 but you can safely turn the short block 5800rpm. The problem is the valve train and the flat tappet cam, which does nothing at the high rpm. Because you have a cat, you would still see a gain in speed with more rpm though, therefore, it's worth looking into.

Dustin

5800-6000 RPM . More in relation to the hyd. roller valve train. The bottom ends have components that would handle more than 6000 RPM.

1.5 XR drive. The prop was originally a 30 bravo repitched, lab finished and stamped 32 by merc. I personally feel it is more like a 31 due to slip numbers that seem unrealistic for the hull. I am hitting 93 fairly easily. I dont believe a five blade would do much for me except overload an already stressed XR. However I would love to try a hydromotive quad 4.

Dustin and MRhorsepower, thanks for your replies. You have confirmed my suspicions.

over all, how do you like your cat, do you get any porposing around 70 or 80, how is it out of the hole. hope you don't mind the questions, but there are not to many profile cat owner's on here.
thanks
larry

No problem. By the way, nice avatar, too bad it wasn't a bit bigger!