If you're going to be towing I think I'd go with the 300s, with your DVs you're going to be pushing plenty of fuel and the 300s won't be quite as smokey as the 370s. Mine without DVs I can make whatever I'm pulling on the trailer turn black if I want to. I can control the smoke, but I have the small pump with stock DVs. However this is with the stock little WH1C, so you're in another ball game with your b2.