I don't think the power is going to be an issue once in boost. From my experience modeling with ricardo and fluidworks, having above ambient pressure behind the intake valve really makes any sort of wave length tuning trival, not to say it won't benefit, but the gains would be small.
I don't know the size of the piping but from the horsepower level you've estimated -- you most likely won't hit choke flow.
The shape could be better, but its not uncommon for production vehichles to have a varience of about 15% lambda from cylinder to cylinder during cruise (one cylinder 14.7:1, other maye at 17:1), most designs will stabalize to about 4-5%, more so of 2-3% for performance applications.
Again, turbos make intake design somewhat simple:
-Air likes to go straight
-Don't make sudden small to large changes (anything over 10* angle will disrupt flow to a point where you want to avoid it)
-Large radius EVERYTHING
Not to say following design principles won't hurt, but with turbocharging/supercharging -- you can over simplify intake manifold design.