Wow trying to get you to understand anything is like banging my head against a wall.
Please learn to read and understand the way a engine and exhaust system work. I have given you some reading material to learn. There is the whole internet that you can learn more from. Type in the google search bar back pressure myth. All you keep coming back with is when you exhaust broke and you lost all your torque. If you really really were reading the links I posted you would understand why you had issues.
To the original poster if you run a cat back exhaust just buy from a good name company. And sorry for clogging up your post.
2006 chevy colorado xtream.
Holiday Rambler 187qb.