I beat Project Horned Owl not too long ago.
I think Irritating Stick can be considered done too. I cleared the TV and Arcade course and there were credits at the end of the Arcade ones. I did not clear the AI courses though. Clearing a course in that mode isn't enough to move on the next one. I cleared up to 49, but it won't let me move on to a higher one. It seems if you're not quick enough, it won't let you move on. I actually did all this last year, then did it again fairly recently.
In case they're interested, I'm going to tag @Splain, @Jeevan and @RH for this post because they were participants in the N64 contest from a while back where we played the Japanese version, Ucchannanchan no Hono no Challenger: Denryu Iraira Bo. The PS1 version seems a lot easier than the N64 version. You don't select the speed of the stick at the beginning. Instead, you can change the speed at any time with the X and square buttons. It almost makes the analog control pointless since it's a lot easier to change your speed with these buttons than with the tilt of the analog. It also give you a bunch of extra lives and continues. There are 3 difficulty settings, but you still get extra lives and continues on hard. Several of the segments seem easier to navigate as well.