From what I understand, I can either:

1 - buy a new OE replacement pump housing for about $500?
2 - send this housing off to be machined and have the stainless liner replaced - $300 (impeller is potentially damaged as well, so possibly $500.
3 - buy magnum pump w/stainless impeller $950

Pros and cons? For speed of getting back on the water, the magnum pump assembly sounds attractive. What do you guys think? How would the magnum pump effect the ski since it's otherwise stock? Riva has these on sale. What would the difference between the 155mm and 160mm be?

im not sure but i believe the magnum pump is only for modified craft with and endurance kit or higher. Check with riva, a month or so ago they had brand new, take off pumps for 300 on ebay. i'd check with them 1st. if you have to buy a new impeller too, you should buy a solas 13/19 or 14/20 if you ski is stock, or if you have the rpm kit a 14/21 is the best pitch.