With most turbo vehicles a free flowing exhaust is helpful.
My E350 is all stock except for the 4 inch turbo back exhaust, my strongest tune is 80hp.
Don't worry 5Star does custom tunes for vans, I'm proof LOL.
As for simplicity of installation of a tune... plug device into OBD2 port and press a few buttons and turn the key when prompted. It's much simpler than the DP tuner I had and was also disappointed with.
Contact them and mention me, not sure if that helps but...maybe?
If I'm not mistaken, they can email different tunes for you to use.