Can anyone point me in the right direction to find a 4" to 5" in PVC for the DWV. I have a 4" lead setup that was never setup right. I had have the adp to switch it over to PVC and plan to route it out the roof correctly. In Chicago, it must increase in size by 1" before coming out of the roof. I rather not go to a 6". If someone can point me to a website or plumbing place that can help me out, that would be great.