I run the spit mono's with Cal-Tracs, and like Dustin, I drive mine on the street regularly. If you back all preload out of the Cal-Tracs, the split mono's then actually act very nice on the street. I agree with Dustin that the aluminum bushings are probobly the biggest part of any change you feel. I noted that they also transfer much more sound into the chassis than rubber bushings do....

To the O.P.: Might as well try them with the XHD's. Calvert told me that the Split Mono's don't really pay off big until performance gets near the 10 second zone.