Experiment - Dual Mopar RT Exhaust with X pipe & suitcase muffler deleted. Mopar Hi flo air filter with Air box lower silencer section deleted. The Resonators are enough muffler for the 3.5L if you like growl at idle and can handle crackle under acceleration(ricer on steroids) but low end torque is significantly reduced. 33 MPG (imp) Hwy. IMO, the RT Exhaust is about as non-restrictive as the V6 semi HEMI can handle before a loss in performance occurs. 2 1/2 " pipe slows exhaust velocity through the x pipe and causes a decrease in low end torque compared to the 2 1/4" Y pipe in stock configuration. Next experiment is to install a Magnaflow 2 1/4 " x pipe from out of the cats and delete suitcase muffler, expand pipe to 2 1/2" just before the resonator pipes for max velocity and scavenging through the x pipe.