Complete turbo back baby! Comes with a 3.5" downpipe that turns into 4" just after it turns to head toward the back of the truck. I had a few friends last night talking about getting a 4" downpipe for their trucks and they just thought oh goodness it's so much better than a 3.5" downpipe. . . I tried to tell them I've talked to a few different exhaust manufacturers and they said they tested several different setups and found that there is nothing helpful gained by going any larger than the turbo outlet. I know the 3.5" downpipe was easier to install than I thought, but it was still a very tight fit....good luck to these size obsessed fellas getting it to fit! I personally do not think it makes a lot of sense with these huge 5 inch or more systems. How much of the exhaust do you actually see? I only see the part of the pipe that goes just over my axle and turns, plus the tip. So....whatever I guess
