i have a 2006 dodge 2500 cummings 5.9 4x4 its has a banks monster muffler and high ram intake and air box wondering if i was to delete resonator/cat,straight pipe to muffler, if i would get better performance and mpg thanks.

 

The resonator doesn't cause any big restriction in the exhaust and you won't see any huge improvement by removing it.

What it DOES do is help with the drone in the cab.