first to describe the motor.- weber 38 Dgas, motor desmogged, header, bosche plugs, glass pack muffler, straight pipes out of header to muffler, and straight pipes out of muffler to exit. (the carb and desmog was PO doing) now to the problems- it really like to backfire, especially when having gears holding back speed (i.e. 3rd down a hill or down shifting ) it has done this noticably since the header was installed. the stock timing doesn't solve the problem with the popping. also i have played with the needles screws on the side (cutting it back to an idle just b4 it dies) but i am not sure if the addresses the richness problem or not. Need to stop backfire, would lik e to know how to set richness on carb and any ideas on how to get the #s down. My readings: Failed because HC= 2.8 (state standards) mine 5.3264 (fail) NOx= 5.3264 (state) mine 7.2395(fail) CO = 80 (satate) mine 18.4293 (well under) *I know its probably imposable without a catalytic converter, or air injection but i don't have them anyway. Help with anything would be great.