if your doing true dual DO NOT use 3" piping,like i said its overkill to say the least.Use 2 1/2 at the most.Thunder bolts or flowmonster are good cheap cats.Also just throwing this out there,I have had true dual straights no or mufflers with shorty headers with the 2 3/4-2 1/4 piping i didnt notice any loss of low end torque I do alot of hauling had 1500 pounds in the bed didnt have any problems going up good size grades,I had 2 55 gallon drums filled with heating oil and 1 33 gallon filled and a oil tank plus a washer.500 for each filled 55 gallon drums and 300 for the 33 gallon,plus the oil tank(good 250lbs plus the sludge at the bottem) and the washer.