Oh it is very cheep. It wors as good as having cats, but the truck runs better, and gives better gas mileage . Mine have been on my truck for at least a year I never got a CEL once I installed them. To gut the cats, you need to remove them. I removed that section of the exhaust. The one closest to the flange can be accessed, no prob., but I had to cut the exhaust pipe off of the side to get to rhe cat. Once I knocked out all the honey comb with a steel rod and a hammer, I welded everything back together. Mine looks like there are still cats, but there is nothing in there you could simply just cut out the cats, and replace then with a section of straight pipe. I wanted mine to look like it still has cats. We don't have emissions testing, but we do have a state inspection. So if they look under the truck, it looks like the cats are still there.