If you can find a bore kit where the id is not so large on the rest of the barrel, it will still give you pretty good acceleration if the porting isn't too heavy. I use the Equation kits. They only have a 0.695" id for their barrel extension and tips. That's pretty small given the fact that I use a 0.696" back on my competition X-ball gun with an Empire kit. I get really good efficiency with the Equation kits and the sound is nice and quiet. Unfortunately they don't make them anymore.
Except for the Automag in front, its usually the man behind the equipment that counts.