Thanks a lot for your help.
Sure, my pleasure. You're on the right track now: it's the marginal-performing lowboy toilet that they installed that's the issue. Put in a Toto of a certain quality, and you're going to be happy with the flush -- any Toto at or north of the Entrada in price is going to do well. The Entrada itself has as good a waste-swallowing ability as any, so it's really a matter of aesthetic design and appeal as far as which one to purchase. You'll get a little-better bowl wash, in my view, from a Toto with the dual-cyclone bowl design, which swirls the water around the bowl from two horizontal jets rather than straight down from rim holes, and the CEFIONTECT coating helps, too, so something like the Drake II (CST454CEFG) is a nice choice. In the country, we have both kinds of toilets (Original Drakes with the GMax flush and the nice-design one-piece Carlyle II with the dual-cyclone flush), and the reality is that they just all perform well. The other four toilets are 1950s-style water hogs in guestrooms and such, which I won't miss now when I replace them. (Before the Totos, I would have lamented the loss of the 5-gallon-flush models.) It was worth paying more for something cool for the master bathroom, but the Drakes work great and look nice in the other rooms.
If you're just not satisfied without that loud Woosh!! that you get from the flushometer, consider a toilet with the Sloan Flushmate pressure tank in porcelain tank. (Avoid at all costs any other manufacturer of a pressure system besides Sloan Valve Company; some of these other manufacturers have now gone out of business because of problems with them; one of our members works in a hotel which installed hundreds of non-Flushmate pressure-vessel toilets, and he spends a disproportionate amount of his time replacing them over and over. I suspect that if he could strangle the person who ordered them (and designed them and manufactured them) he would do so very, very slowly.)
Gerber UltraFlush seems to be Terry's preferred one. However, DO NOT acquire the dual-flush version or any version that has something other than the Sloan Flushmate in it, all of which Gerber offers. I think the thing is ugly, but that's just me. American Standard makes a pressure-assist Cadet that uses the Flushmate. A concern about them is that their porcelain-firing consistency and quality control really sucked a few years ago, with lots of toilets put out into the marketplace that I wouldn't find to be acceptable. Now that they are no longer owned by a hedge fund but instead by a Japanese plumbing manufacturer, word is that that quality is improving, but it's still a risk.
Although the Flushmate toilets look like a gravity toilet from the outside, the "tank" is just a container for the pressure-assist vessel. The bowl design is completely-different, so if you didn't like the noise, you wouldn't just be able to remove the pressure vessel and use the porcelain tank to hold water and a traditional fill valve and flapper. If you did so, as some enterprising folks have found, all that would happen is that you would flush and the water would just sit there. The bowl is designed so that water must come in under pressure or it won't work. (If you try the reverse on a gravity bowl, the water will spray all over the room, so there's a reason the pressure bowls are designed differently.)
One note: on rare occasion, and the consensus is that it's been fixed now, these things have exploded. My favorite youtube video of one (most are like pissed off concerned parents) is the lighthearted Las Vegas Killer Toilet video, in which you can see the black (presumably-) Flushmate with a hunk missing still attached to the bowl, where it has shattered the porcelain tank and sent pieces all over the room. Nobody was actually hurt because it blew while the bathroom was unoccupied. It's probably as likely as being in a plane crash, but it's something that can't happen with a gravity bowl...
And here's a much-linked-to thread from this website from around the time the recall first hit.
https://terrylove.com/forums/index....flushing-system-for-toilets.47517/#post348515