I'm about to install my American racing headers American mads and of stainless steel they have a slip on collector, can be 3 in or 3.5in I got the 2" into 3in . Before it snowed i Fit tested each tube and they should fit fine. I'm installing them as one I'll let you know how it goes I paid a lot for them but I shouldn't ever have to replace them hopefully. Any one try these yet? I waited ovrr a month to have them build. And the quality looks top notch. $1500 or 140 a month for a year.they helped me finance it too.