Jim Beaver wrote:

Are the internal workings of the bowl-to-waste-pipe path standard from
company to company, or is there a wide range of variations? How can I
replace this toilet and be assured that the same problem won't result?

Fill a 5 gal bucket with water and pour it quickly into the bowl. If you get a
sarisfactory "swoosh" as the bowl empties, you don't have a drain issue.

Water pressure is immaterial - the flush comes from the storage tank. Pressure
just affects the refill time.

Builder special toilets are notorious for pour hydraulics. I have a couple of
Sterling's (made by Kohler) that are horrible. Replaced 2 of them with
Kohler Wellworth Lights that work fine. If you want to replace it, pick up a
copy of the latest Maximum Performance Test of low flow toilets he

http://www.cwwa.ca/home_e.asp

Look for the link that says "6 Litre Toilets" and then click on the full
report.