The drivers side is 2 inch for about 18 inches. I would have to measure. Then 2 1/4 to the muffler. Idk how he got 1 7/8s. Pass side is 2 1/4 all the way. Here is a pic of the drivers side. The pipe is flattened some to go past the T bar. Then 2 1/4 after that. The pipes are also flattened on the bottom in a couple of places. Pass pipe pic in the middle. Other pipe is 71 up Walker brand. Kim