Though i must admit it aint the best at all but for the price i bought an ozito fresh water pump for 100 buks from bunnings. Definetely not high pressure but much better than the original and i can replace it three times by the time i have bought one "marine" washdown pump.

 I have the jabsco 4.0 which i find great but the hose hand piece is what makes it crap replace it with a standard garden hose nossle or a high pressure nossle and it works much better. Might save you a few bucks. Unless yours is knackered then im not sure. 

 there is other things that can be done before you jump in and replace the system as most pumps are pretty much a muchness when it comes to LPM  but have a look at the Shure Flow there pretty hardy if you wanna upgrade, but like metioned look at your nozzel to

Gday Pricey, Ive tried heaps of different pumps, and like Epic has said, they are pretty much all alike. But by far the best for pure flow rate and pressure is the old forward facing tube pick up that operates when you're moving - no pump. Just be sure to put in a SS ball valve at the pick up. I would use it as we were coming home as it would blast gunk off, then just use the pump driven set up to wash the suds off etc. Works well as you cant help clean the boat if your driving!
Daisy

 Have a jabsco 6.0 - works fine.

 cheers guys. I'll try switching out the hose and nozel. That forward facing pick up is a good idea as well I might try that