Did you have Virgil retune it after the converter? If not you really need too. I had my Circle D 3000 put in about a month ago and retuned last week. night and day difference. Just like if you change the cam you have to retune to get optimal results.
2002 Silverado 5.3 Flex Fuel SCSB AEM BRUTE FORCE INTAKE, 160 THERMO, HOOKER LT'S, Y PIPE INTO DYNOMAX RACE BULLET, THUNDER RACING 220 .551 114 CAM, NEW 918'S, 7.4 COMP PUSHRODS, LS2 TIMING CHAIN, 3.42 GEARS, AUBURN LSD, CIRCLE D CONVERTER, ZEX 125 WET SHOT AND TUNED BY TIM AT REDLINE PERFORMANCE IN FESTUS, MO.