One is a resonator, the other is a muffler?
Yes, technically Vibrant advertises the 1142 as a resonator and the 1103 as a muffler, but from talking with their engineer, they share identical construction, and only differ in the overall size/volume. They both have the same 3" ID inlet and outlet to slip over your 3" OD piping, both are 304SS, both use a perforated, straight thru core design with their propriety packing materials, and the muffler casing design is identical with the 1103 being a larger 5"x 9" oval and 15" long vs the 1142 being 4"x 6" and 9.75" long.