I can confirm that the Aeroslave pipe is very good with the OS 160 in pattern applications.
The top revs you mention(8--8-1/2K) are what we get with pattern props(APC17*12,15.5*12 4blade,Engel 18*11carbon),with a good transition.
Not quite as quiet as the Greve Ali. pipe, but more top end and a faster spool up.
I think your problem might arise in selecting a3D prop to load the motor to the top revs you want.
An alternative approach might be to check out what Weston UK have in the way of mini, "torque" pipes.
I don't have personal experience of them in this size of motor, but they have a big range, and they certainly work well in the smaller sizes.