My dilemma (back firing)

From : tom lawrence

Q: i have a 1995 dodge ram 318 from canada this is what i have done to it. now occasionaly it will backfire and scare the daylights out of me. wondering if anyone has any light they can shed on the situation. yeah - the engine has zero backpressure now... at lower rpms the exhaust valve is open long enough to allow the scavenging effect to pull raw fuel through the combustion chamber into the exhaust. street-driven engines need a certain amount of backpressure to run properly. put a non-gutted cat back on and your problems will most likely disappear. .