Before I got seriously into bowling, but they had some of the highest differentials around. 0.075, brushing near the 0.08 limit. I think they were banned from PBA competition, but having just checked the PBA approved ball list, there are three listed, the SD-73, the Limited Edition, and the Pearl.
Probably decent enough balls in their day, the LE was released (err, PBA approved) in mid '03, the others in '01. I'll bet they're worth decent money, especially if they're new.
SH