The magic screw in the brand new mixer which is not behind the plug yet is the idle air mixture adjustment and it is adjusted full lean. I can see my dwell is 101% through the MCFA diagnostic software. My Tune up is fresh and perfect. My question remains the same!!! Is there a fundamental difference between the standard cobra and the OEM cobra supplied by Cat for the S15G fuel system. So far the only difference I can see is the cover. Impco's website is useless. The fuel control is verified as 100% functional. The only thing is is making any sense is there must be a difference in the regulators