Toilet w/3" flush valve into 3" drain pipe

I've been thinking of replacing my old 5 gal/flush toilet with something like the Toto Ultramax. It apparently has a 3" flush valve. I just realized tonight that my drain lines are 3" PVC instead of 4".

Will I have any problems using a toilet like this with my existing plumbing?

Thanks for the help...JR

no

no problem with that.

The trapway is still smaller than that...the large flapper is what gives it the initial volume to get a good flush and build up a head.