I have M-22's a vp- 100 and a HSU STF-2.My problem is the vp-100 does'nt disperse the dialogue wide enough.My sitting position is ok,but my wife's chair is about 35* off center.Her hearing is great but still has a problem hearing the dialogue.Would the vp-150 make it better?

I wonder what would happen if you tried this first. Her seat must be close to being right on-axis with one of your M22's. We all know how clear they are. Turn off the center channel in your receiver's setup menu. If the dialogue is clearer, then it seems like maybe, possibly, probably, it IS a dispersion problem with the VP-100.

Her chair is almost right in front of the left main,and I did try it with out the center and she said it was better.

Frank, this may be an example of why I don't care for horizontal MTM centers. As another experiment(besides using the "phantom" center), set it on its end in a vertical orientation to see if this significantly improves the horizontal dispersion. If not, or if that positioning isn't acceptable for permanent use(even below the screen), then simply increasing the volume of the center channel by 2-3db may help. Of course, you shouldn't do anything which would reduce your enjoyment in the preferred center position which is yours by right.