PMK has a short life once it is mixed into a working solution and put to use. In extended-time tests with sheet film processed in trays, I found that it poops out after about 16 minutes due to oxidation. I found that I could get a decent N+1 out of it at the 1:2:100 dilution, but getting to N+2 was difficult. 2:2:100 would double the amount of developing ingredients at the same PH and presumably increase the contrast of the film over the same amount of time as the normal dilution. Increasing the part B would increase the PH of the solution, which might boost contrast, or it might increase fog. You'll have to see for yourself. PMK produces different amounts of visible stain with different films, so it's difficult to predict without actually trying it.
Information I found about developing times varied widely depending on film type, exposure, development method, agitation. You really have to determine what works best for your own methods. In most cases, I found that about 9 minutes worked pretty well for me using Tri-X and T-Max 100. Delta 100 develops much more rapidly, about 6.5 minutes for normal, all at 1:2:100 dilution, 70 degrees F.