The STM 3″ Stainless Steel Downpipe for the AWD 2G DSM will bolt up to any stock location test pipe/cat and o2 housing with 3″ 2-bolt flange. This is a perfect match for the STM O2 Housings and Test Pipes. Fully 3″ stainless steel, STM pipes are tig welded, back purged and made in the USA.