Doug,

Well this is the point!
The Tower/Hobbico .46 silencer is 'semi-tuned' and does not have a baffle of any kind.

It adds RPM, when compared to a standard OS 783 silencer, for example; even if the OS' silencer had its baffle removed.

But maybe when compared to open-exhaust figures, it is still just a restrictive muffler, not a real tuned-pipe.

But just getting the bolts loose and having some of the back-pressure escape from the joint, does not constitute an open-exhaust situation in my book...