Ok here is what I have found...
I spoke to Spal today as well as Brian at Custom Aluminum Radiators in Kingman. Spal recommends them for radiators, fans, and shrouds. Spal does not sell shrouds because there are so many fans and size variations it wouldn't be cost effective so they give that to the radiator shops.
Brian from Custom Aluminum Radiators gave me an education on cooling systems and how it all works together in harmony. As far as the shroud goes he doesn't think we need one on this type of fan. I am just telling you what I have been told. I am not saying this is accurate info. Call and discuss this with these guys if you would like. The plastic case that surrounds the fan is sufficient. It has to do with the recycling of air off of the tips of the fan blade and the venturi affect to suck air through the radiator. In some cases the where the fan blades stick out past the plastic housing you would need a shroud. I don’t know if we have a cooling problem with the XTZ 1000 because mine has been good so far. I have not seen ambient temperatures above 90 degrees yet though so time will tell. I know there are a few guys having issues but it seems to be linked to improper head torque or air in the system. Once those two are fixed it has not been a problem as far as I can tell. If someone has the ability to check the return water temperature on their XTZ 1000 and post some numbers that would be a big help in determining if there is a potential overheat problem. Mine is in the shop for the axle issues so I can’t perform any checks. Also shoot the radiator core with a temp gun and make a note of that as well. The radiator seems to be very large compared the 650 and 700 so I have to think the overheat issue is limited. There is a larger fan from Spal that looks as though it would fit in place of the stock one. The stock one is listed on Spal’s site as VA11-AP7/C – 57 A it has a current input max of 9.5 amps and pulls a max 1350 cfm. The one I was looking at as a replacement is Spal VA10-AP50/C – 61 A which has a current input max of 13.6 amps and a max cfm of 2270. I think the XTZ is good for 25 amps max? With lights on and fan at full speed I don’t know if it can handle it. Someone chime in if they can run the numbers and figure this out.
Custom Aluminum Radiators - Brian