i believe you can remove the viscous unit altogether, but someone correct me if im wrong. if all else fails, just take a hack saw to it. be absolutely sure you want to do it though, because as i just found out, water pumps are expensive.
if you get some slim fans and make a slim mounting of some description you should be able to slide them in without removing the viscous unit, but theres obviously a lot more room if you do. also, most fans dont have a set polarity (ie you can run them both ways), but its always worth checking they can.
im guessing youve read my installation plan on the downloads. if so, just follow that, you shouldnt have any issues, but if you do, just shout