Okay the link works now. Dr Gas also makes kits to build your own and that maybe what the guy is trying to sell you.
sorry man, the hooker x pipe recently proved to be the best flowing on the marketDr Gas is manufactured by Pro-Motorsports out of Sandy Utah. He is the originator of the X-pipe and builds the best X-pipe in the business. He is a little pricey, so $40 is a deal if it fits, This is the unit that all the Nascar guys use. He has slowly built his business and is a very good engineer when comes to building innovative products. You can go to www.pro-motorsports.com or you can go directly to Dr.Gas I've bought a lot stuff from these guys for my 67 Coupe vintage race car. I also than their 3 1/2" X-Pipe on my Boss 302 with side exit exhaust. I highly recommend them.
Hope this helps