Adapter Kit allows Borla(r) Cat-Back(tm)140837 140837BC &. 140837CF to be used on '21-'23 Mustang Mach 1. Adapter Kit includes 2) 2.25" inlet x 2.75" outlet x 5" long adapters and 4) clamps. See below for Product Features &. Benefits. Borla products are constructed using T-304 stainless steel for long life and sharp appearance and feature all welded construction for maximum durability.. Borla products are constructed using T-304 stainless steel for long life and sharp appearance and feature all welded construction for maximum durability.