How does an 850 dual feed double pumper compare performance wise to a factory six pack set up. Consider that the 850 would have a good aluminum aftermarket intake. The 850's i have had in the past were trouble free and worked great when new. I have also had 2 diff six pack set ups-one worked/ran great, the other one ran so so. Do the 440 six pack carbs flow more air/fuel than the 340 carbs.