I got done welding in a mil spec certified flex pipe on my catback. Their exhaust is very nice, but it could've had thicker flanges and a better section of flex pipe for the price. Stainless flanges and flex would've also been a plus. I'm happy they make this exhaust, otherwise i'd have had to drive real far to a shop with a mandrel bender. You could also convert back over to the stock spring bolt setup with a donut gasket. I feel that I should've went that route because it would probably last longer and it's way cheaper. The company I purchased is made in the usa and seems to be the only mil-spec certified flex pipe out there. I could've got away with the six inch, but I purchased the eight because I wanted to get it right the first time. I'd imagine shorter is better, but who knows. AF2508bss stainless works is the part number and manufacturer. I had to purchase flux cored stainless welding wire, and a flange with a small section of pipe attached to it. The pipe was sixty, the wire was forty and the flange was fifteen dollars. I purchased two flanges because eventually i'll have to replace the one on the y pipe as it's rust pitted bad. It's a huge difference using thicker flanges, they don't flex and leak when you tighten them. I never thought i'd spend over a grand on an exhaust in the end to get it right, but with band clamps and the full exhaust from the manifolds back i'm in it over a grand.