575 exhaust on motortrend car fix

Not having bypass valves will cause the burbling and pops. Caused by creating a partial vacuum in the exhaust system when you lift the throttle. Air rushes in and ignites the rich mixture in the pipes. With bypass valves, you lift the throttle and the bypass valves slam shut, cutting off the inflow of air into the shortcut back to the exhaust.

 

My 575 has loud cracks and burbles off throttle and between shifts and it is still running the factory manifolds/pre-cats.

 

The cracks and burbles do not really have much to do with the forward part of the exhaust. They are caused when the throttle is lifted and creates a partial vacuum in the rear pipes. Cold air rushes in and ignites the mixture in the rear exhaust. Does not happen with valves because they slam shut when you lift the throttle, so no extra air. I had full OEM, full catted, straight center pipe exhaust on mine except for unvalved Novitec Super Sport rear mufflers. Loud enough to wake the dead and popped and burbled whenever you lifted the throttle. 90 mm tailpipes compared to ~72 mm for OEM.