Been running the Fullsac mod on my '03 RKC for about 3 months now. If your stock head pipes are in good shape, then it's a cheap way to a true dual exhaust. Besides having two distinct exhaust notes, the done is also deeper sounding now too. Lastly, the heat reduction on the right side is very significant, and would be reason enough to do away with the stock "H" pipe.
The entire mod start to finish took about 1.5 hrs to complete...piece of cake.
-Dusty