I know this is not Buick related, anyway went with the 3" Dynomax Super Turbo Exhaust on my 2005 GMC Yucon. Runs and performs better and has a more aggressive exhaust note slightly more the stock. I replace the system because of failing cats. If anyone is going to pull an exhaust off one of these trucks there in for surprises, get out the blue wrench and saws all !
