There are threads in the DIY forum on Maxi-Jet mods. That one looks a little different from the ones I've seen, but you could do some searching there. Some of the mods do give a large boost in efficiency.
"With 15 minutes time and almost no tools you can modify your Maxi jet 900 from 230 gph to 1,600 GPH and the Maxi jet 1200 from 295gph to 2,000 GPH !!! The flow is also dispersed in an extremely wide flow pattern to insure that you are getting the proper flow but with out the direct force some of the other high flow pumps on the market produce."