I agree that you will want to boost using DME rather than a partial mash. That having been said depending on how much of a boost you are looking for, it may have an effect on the IBU's. You can plug your recipe into calculator as it is, then add DME and see how it effects the rest of the numbers as you go. If you are looking to go from 4% to 6% it will most likely change the balance of the beer if you only adjust gravity.
In the botte: Wheat, American Pale Ale
In Primary #1: Light Hybrid #1
Primary #2: Light Hybrid #2
On Deck: IPA
In Design: California Common