I tried to order the E series white bros. and i was told it was discontinued. Had found a real good price too. Is the supper trapp the same system,the price seemed resonable? Same system? No. Reasonably priced? Yes. It's probably the best slip-on for the XRL, my opinion of course. I have the IDS2 QC. It's well-made, lightweight, has disc tuning, provides good low-end performance, and it's not too loud. And it won't melt or discolor your plastic.