adj ws spring perch is a Ned Ritchie item, but yopu have to have some machine work done to a 70mmX12X125 bolt to make it work (about 60.00).... I have a "problem" with my cat as well, but I pass emmisions (state run) just fine with the 272, but please ck with Ned on this one, I'm not going to be the guy to tell you yes for sure.... Scott