When I had my 2.25 inch system done, I found out that the custom shop (R&D Exhaust in Billerica, MA) I was at used hot-rolled alluminized pipe. I am a mechanical engineer, so naturally I checked it out. Hot-rolled aluminized pipe last up to 5 years on MA State plow trucks and school buses....5 years of salty roads in rain, ice and snow.
Conventional Midas cold-rolled aluminized pipe will show rust on the weld seam w/in one winter.
That is why some custom shop jobs can last so long. It is a good idea that check with the shop first.
