3" Exhaust Upgrade?

the more an engine can breath the better. that back pressure myth is still going around but just ignore it. only 2 strokes require backpressure and i dont think you 347 is a 2 stroke.

that should be one fast motor!!

i dont know about ALL 2 strokes but i know they have power valves that opene and close with the backpressure pulse of the exhaust, if you run no exhaust, they can get stuck open. 2 strokes really dont have any valves except those 2 exhaust. im not too familiar with them, i just know that the back pressure on a 4 stroke is a myth. y dont we all just run 8 catalytic converters and 6 mufflers and get the most back pressure we can get? lol.

Sounds like a good combo you got there but my buddy has a 331 with the 3 inch flowmaster kit and it doesnt sound all good it you want to sound better then i would go wh the SPINTECH SUPER PRO STREET mufflers i have heard those on a biut 5.o and they sound awesome thats my next move for sure.

you loose lower rpm exhaust velocity with a larger dia pipe this reduces scavenging. Think of scavenging like a siphoning effect, keping the exhaust gases flowing and clearing the cylinders. The problem with too large of a dia. for the particular application is you are now pushing the gases instead of pulling. you will make gains like stated in the higher rpm range but kill your lower off the line power. ttopstang backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect like I stated. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. This all gets tossed out the window for turbo cars, but we aren't talking about one. it's all about finding the happy meduim.