So... the griffin one from novak??? I know its a LOT of money, but IMHO, its worth it. It fits nicely, and even with just 2 stock XJ fans, the LS2 runs at 195-210 all of the time, even in the scorching 100+* weather we have been having here in Chattanooga.
The only other option would to be to grab a 3 core from a parts store. Dan (MELKORsXJ) just swapped his factory one out for a 3 core, and its the coldest running 4.0 I have seen... ever. Hovever, its half the price of the Novak one. This can be looked at 2 ways though... if it works, you saved $250. If it doesn't, you are out quite a bit and still have to do the work over as well as spend the money for the griffin. I don't know your money situation, but if I were you I'd probably just get the Novak, but then again, I have personal experience with it so I may be a little biased.