There was a dyno that mobile dyno or dyno edge or someone posted. It showed a lose in hp with the dmc two into one pipe. The set that has the single silencer but two pipes. That doesn't mean is going to be the same on all motors. If you like them, you like them. It may work on your machine but not another. Like always, there are a lot of factors. If there was always only one best, there'd be very few aftermarket parts.