Does anyone have the Borla full exhaust cat back system including x pipe? The Borla CSR sent me an email stating performance improvement of 5-7% for 2011 Mustang? Are you seeing that? Does that make sense? Do you know the Borla pipe sizes verses stock? These systems are very expensive (~$1250), not sure it is worth it $$, but 5-7% performance improvement would help justify the price. I have been told FRRPP, Shelby oem some of their parts from Borla. Thanks.