i will never do any thing less than 2.5 on any of my toys. 2.25 is good for the street and mpgs or if you are going to run a short exaust ussally ending right behind the cab. but 2.5 for better sound and power. you cant run a 2.5 straight pipe other wise you will lose power. with 2.5 you have to run it all the wat to the back with some bends to make some back pressure.
