Versatile Exhaust Pipe Expander Tool Set. Small Expander: 1-1/8" to 1-3/4" (29-44 mm). Large Expander: 2-1/8" to 3-1/2" (54-87 mm). 1x Small Expander. 1x Large Expander. To achieve optimal results, ensure that at least three-quarters of the expander is inserted into the pipe.