Banks Intake and exhaust system

When I bought my 2005 Coachmen , the previous owner had installed the full banks system. From air ram to headers to full exhaust and tranny shifting module. It definitely increased acceleration and improved the power curve. I'm happy I have it; but could not justify the cost of installing the full system myself. My tranny is a four speed with OD. The newer V10's have a little more horsepower and matched to the newer trannys 5-6 speed with O/D probably match the power and increased fuel mileage I get with the banks system. Realistic mileage is 8-9 mpg downhill with a tail wind and a moderate foot on the gas pedal while towing our Jeep Compass. The banks system does provide better mileage and acceleration on a diesel engine over the V10 gas. Class A mpg is very subjective and has a number of variables effecting it; terrain, GVWR, wind, height, tires, speed, traffic, heavy foot, City/Hwy, generator use, a/c, idling, etc..etc.etc..