may not want to hear the answer on this because I already ran about 16 feet of it in my crawl space but double checking.
used that 3" PVC pipe that has the thinner wall (also a "flange" at one end where you can put 10' pieces together).
have a nice slope and it drains very well (water anyway).
the guy at Home Depot said I can use it for a toilet drain -- is he right ? !
thinking about it now, I wonder if you have to use the thicker schedule 40 instead?
actually, I do plan on using sched 40 from the toilet and then about 6 feet later, coupling to the sched 30, and doinf the same on the other end that ties to the main drain.