I bought a gas stove off craigslist and he gave me some venting pipe with it. The pope is interesting to me, it come out a 4" and empties into a 6". He said it gives out extra hear this way? It seems like a factory setup, but I'm new to gas stoves. Can I continue with 6" till I exit the house then step it to 4" with the adapter he have me? I'm adding a couple pictures if they will upload, so you can get the jis of what I'm talking about.