I will be installing a large range hood over my range. I dont have the hood yet. However I have the drywall down on my ceiling and I would like to rough in my vent pipes for the hood. The stove is not on an exterior wall so I need to run my vent over about 6', make a 90degree turn, over 6 more feet then out through the wall. I have a large soffit over the cabinets where i will run this through. Question is, what do I use for vent pipe? Do I use the flexible stuff used on a dryer vent? or do I need something different? All the hoods i have been looking at are 6" round.