I have an Eelco progressive on my 6x2, Elelbrock are rereleasing the X-1 and have progressive linkages to suit. If street use a progressive linkage is the way to go as you run on centre 2 until 65% throttle when the others cut in. Don't use a direct linkage on the street as ALL carbs will work simultaneously. There is slight differences I believe between 94 and 97 setup so you need to choose the rights carbs, manifold and linkage that suits you.