Good afternoon. Needed help with this replumbing project. I opened up walls and figured why not right? I want to keep the same bathroom layout. Vanity and tub/shower has 1.5in drain pipes. Toilet has 4in drain and main stack is 4in. The vanity and tub/shower are not individually vented. That's the basic situation. I do have pics and a video below. My question is, should I keep the same sizes? Should I switch anything like fittings? Should I rerun the pipes through the middle of joists? I will replace with ABS. I will also add a vent for the vanity and tie into the main stack. I will also do this for the kitchen sink as it wasn't vented also. Any suggestions will be appreciated. Thanks. Old pipe tying in will be removed. Main stack with toilet above Vanity Pipe coming from the right flowing left Tub/Shower going to a Tee where the vanity ties in on the right and flowing to the left of the Tee to the toilet pipe/main stack.