I needed to put a new exhaust system on my k5 so I started looking around for something I liked. I have a dual 2.5 setup on my 71 truck and I love it, so i figured i would try to do something like that with my k5. Looked around and only found two options. The Dynomax Kit which was 110 and another one that was stainless that was about 400. Knowing that i would want headers in the future i went ahead and got them. I choose the dynomax coated headers and their dual kit for their cost and warranty. A local shop was out of the question because I'm doing away with my cat's until i can afford some high flow one's so no one will touch it. I called the tech line at Dynomax to find out what headers i needed because the listing in JEGs didn't include a 91 but i knew that the trucks were the same in 87. So i call to make sure of what header i needed, when i talked to the guy he assured me that they would fit a 91K5 4x4 with no problems. I get my parts in and bring the blazer to the shop to have the headers put on (Lack of time or i would have done it myself) Go to pick it up that afternoon after work and the guy says that they are the wrong header's for my truck. Now i'm starting to get hacked. So i start talking to him and he said that he was able to get them to fit but he had to remove the bump stop for the diff. housing. This isn't a problem for me becuase there isn't anything in my area high enough to make my truck need that much flex. So i bring the truck home and begin to put the dual kit on it. THE PIPES DON'T FIT!!!! the passenger side works fine but there is no way in hell that the drivers side will fit. Now i must wait till moday so i can get a shop to modify or make me a new pipe that will fit. This experience with dynomax has turned me off to there products for good. What is the use of having a tech staff if they don't know what they are talking about. I know i have read about many people putting this product on and not having any problems but i am having hell with it. So be warned the dynomax dual kits are not all that and a bag of chips.