I have RM-2's and have tried turning the PR slot in all 4 directions. Rearward was working best for me also, with respect to bass response and sound clarity.
Since then I have removed the factory slot/chamber and replaced it with my own. My new chamber has all 4 sides closed, not just 3. Each of the 4 side panels has 5 holes, 1.5" diameter. I plug most of the holes, but leave about 5 or 6 open, on the sides of my choice. With this setup I can direct the PR energy into the room in any direction desired, with pinpoint accuracy. The net result is an enhanced sound stage, and increased bass and clarity.
Currently I have all 5 rear holes open, and 1.5 holes open on the side facing the oposite speaker. Yes, as little as 1/2 hole makes a difference in the sound.
My new chamber also provides a built-in upward tilt of about 6 degrees. This permanently tilts the speak up at the listener. Sound is way more clear and distinct with the cabinet tilted upward.
The new chamber also has 4 leveling screws on the corners. The screws cut thru my thick carpet and engage the concrete floor. Speaker height has not changed. Without the spikes the speakers rock back and forth way too much. Not any more with the spikes. Using 200# of plates on tope of each speaker helps in that regard also. The sound has more backbone with the weights on top.
With the new PR box I gradually removed all the putty from the PR. I can do this because all 4 sides are removable with screws. With all the putty gone the sound is punchier/quicker and cleaner, with minimal loss in bass response.
Happy experimenting.
Dave
