you can use pretty much any type of rubber hose. it doesnt see that much heat i dont think.
i used the same type of rubber automotive hose you can get anywhere. if your installing an offroad h-pipe maybe you should get rid of all your smog too and get rid of it all together?
i think i used a fuel hose?... i really dont know... any hose is ok ... just take a piece of the cut egr tube and run down to home depot or osh... get about 6" ... you will use about 1-2"
The true stock setup is actuallyclamped there with a similar style clamp to a muffler clamp if I remmeber right. It's very small, but usually if you can get it undone, a little tugging will get the pipe seperated.