Description 41908, 41937, 41700, 41917, 41918, 41890, 41891, 41845, 41844, 41515 Need help? Here’s a quick lesson on automotive exhaust pipe sizing: – Components such as mufflers, catalytic converters and resonators are generally measured in I.D. sizes. – Pipes such as extension pipes and tail pipes are measured in O.D. sizes. Although both part types possess the same advertised diameter, pipes are meant to slide into components.
