For GM LS engine swaps into 1982-2004 S-10 2WD trucks 1-5/8†mandrel bent primary tubes and 2-1/2†collectors constructed of 304 stainless steel for strength and durability 3/8†thick header flanges for a leak-free seal Premium gaskets and hardware included 2-1/2†reducers with oxygen sensor bungs included Available in natural 304 stainless steel and polished 304 stainless steel