Your doing this all wrong. With the mods listed in your sig, your not a candidate for a 2 into 1 carb. Your running a mid-top pipe, and a mid-top intake setup. The single carb kit only makes more power than dual carbs right off idle to about 5,800 rpm. Your mis-matching the working power ranges on your parts.
Hope you have a dremel, cause if you buy one, the v-force stuffers have to be match ported to the intake, and you have to take material off the intake as well.