they way you describe the exhaust ..etc...there is NO question the carb is way tooo FAT ( RICH)...What size front and rear jets do you have ?
remember fuel pressure at the regulator will not determine the lean or richness of your carb..only your main jets...and if you have a power valve it could effect the rich side your smelling...
you also need to bring that fuel pressure up to a minimum of 6 to 6.5 lbs sitting there idling..remember you got it dead headed sitting there against the regulator..so it will drop a minimum of 1 lb or more under full throttle....anything under 4lbs is dangerous of burning an engine up...even the factory Hobb switches ( fuel saftey switch) is pre-set at 4lbs from the factory...this means when the fuel pressure hits the 4lb mark the hobb switch will kill the circuit its wired to stopping everything in its tracks...most hobb switches are wired into the NOS fuel side for extra saftey in killing the NOS in case the fuel pressure drops to a un-safe level ( 4 lbs )
Brian
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "