Where can i purchase perforated stainless 304 tubing. I need 4". It is the stuff used on the interior of mufflers as seen here:
http://www.lachoppers.com/perf.php

 

McMaster-Carr has perforated sheets of varying thicknesses, hole size, spacing pattern, and amount of open area. You could probably roll your own tube and weld the seam.

After checking the link, you'll have to search. I found 304 stainless perforated sheet by clicking on the "stainless" button under materials.


http://www.mcmaster.com/#perforated-metal/=1ch8ds