Ok, the wife has me raising the ceiling in the kitchen by not raising the drain pipes, We still gained 4 inches of space. My question to some plumbers is this...My plumbing is dead flat in many areas of this ceiling. Haven't had any issues but what would be the risks of raising the pipes roughly 3 inches higher? I have some pics but you couldn't tell probably what it is because of the image sizes that are allowed here. Basically since I have flat areas (Two that are about 5-6 foot each) going to the main drain, If I raise all the pipes 3 inches. Will that change the flow enough that it won't get enough water flowing going at first to get it all the way down that 6 feet of flat pipe? I just don't want a flow problem and have to get the plunger out every time I use the head.
Since you're addressing drain pipe slope, it needs to be 1/4" per linear foot sloping toward the main drain. That's obviously 1.5" from one end ot the other in a "flat" 6' run, or sooner or later, you're going to have clogging problems.
You need to plan this out to eliminate flat runs in the drain lines.