You can still get the mini maxx , since it has the capability to run both with factory emissions or in off road use, you do have to sign the waiver for not to be used on registered vehicle , same with most of the exhaust systems you would need to go with it. I went with the 5" turbo back with performance muffler from flow pro, price was great and the sound is perfect , no drone when towing, not much louder than factory in the cab, only gets loud when hammering down on it. Averaging 17.5 mpg running 37 13.5 toyos