A single will get you a little more power right off the bottom, but it will cap the top end quite a bit. You wont notice the increase in low end power, but you will notice the increased acceleration speed. I used to run the 2 into 1, and I have quite a few bikes I built running it. However, I recommend dual carbs. My dyno test showed the dual carbs having 4.75hp more on the top end than the single. On the bottom, the difference was only 1.56hp with the single being the one that had more.