8-9 psi fuel pressure is higher than necessary, but dropping to 2-3 psi will cause a problem. You need constant pressure going down the track. The rubber tube will make sure that you aren't pulling fuel out of the vents and dumping it into the venturi's. The jet extensions will make sure that the secondary jets stay covered with fuel. Putting a bigger carb on will probably help make more power, but will not change anything with the surging.
this problem of the vents , will solve with the tube .. but can't cause a drop pressure ... i think
