Have an 03 Durango SLT with 4.7, 3:55, auto 61,000 miles. Will a dual exhaust with stright thru muffler hiflo cats (2) improve milage? If so to what? What size pipes.... use orlginal spech o2 sensers? What type of mufflers? Any Ideas?
bob

 

no it will not improve gas mileage, the stock cat is already a hi-flow unit, and you most likely dont have enough oxygen sensors to run the truck properly in this configuration (you need 4 of them which is only the california emissions package has)