So I was trying to test some theories on why the Smiley Navel fight is faster on the JP version and stumbled upon a trick that allows for a 3-cycle kill! This is on the NA version of the game, so not only will this trick allow for a huge time save on the current WR, but calls into question which version of the game has a faster time potential. It may be that the JP version can achieve a 2-cycle kill with this trick and would still be the faster version, but if not, the NA version is likely faster due to the bonus game text skip.

I will post video evidence of the trick (hopefully in the form of a new WR) soon.

Awesome, it's always great to have new runners and new tech finds!

That very well may put NA back in the running as fastest just because of that bonus game menu text.

There is also the one enemy in the top of the memory cave that takes one less hit in NA version..

Here's the video evidence (Thanks sYn for clipping it!):

The 3-cycle is hard to reproduce on the NA version, leading me to believe that more than 2 hits are registering on at least one cycle. If we can figure out more about how exactly this works a 2-cycle may very well be possible especially on the JP version.

To follow back up and provide some closure, I've gotten more consistent at reproducing the 3-cycle on the NA version of the game and I believe the key is making sure Bonk is fully rotated downwards and not still spinning when hitting the boss to make sure full damage is applied on each hit.

The JP version of the game can still save time 3-cycling as only a standing headbutt is needed instead of the downward air hit to get enough damage in. This results in the ability to use RAGE! quicker since you don't have to wait for knockback and landing on the ground. I don't believe downward headbutts will do enough extra damage to make a 2-cycle kill possible on the JP version but have not tested for myself.

So in conclusion the 3-cycle is harder to pull off and a bit slower on the NA version, but with the other time saves available to the NA version probably makes both versions about even as far as best possible time.

Update: This strat had been superseded by the Infinite Invisibility glitch strat which allows for a 2-Cycle Smiley Navel fight and saves about 20 seconds over the previous best-known boss rush strats! One very important thing is that in the JP version of the game you can still be damaged by enemies while invisible which makes this strat more difficult, especially against Bacty.