Last night I installed OEM plug wires and 1/2 tank of premium fuel. This helped against the bucking but the truck still shows declining & variable oil pressure at constant speed. The truck has have a new (5,000mi) long block and new Weber 32/36 but the rest is (for now) stock. Could constricted exhaust from an ancient catalytic converter kill my oil pressure at speed? Please help. <img src="/forums/images/graemlins/cheers.gif" alt="" />