so i now have my new genorator ready for mounting in the van

The problem i now have is venting the exhaust fumes out of the van
I am looking for some sort of flexi heat resitsant hose to be able to connect to the exhaust port and then drop down through the floor of the van

as you can see its only about an inch dia ,
have any of you guys got and tips or links or have done anything like this before ? HELP !
Andy