This strategy if I'm correct saves a framerule over the other strat, to grab the mushroom in 1-3 or whatever. Basically you hit the side of the koopa so you have to slow down a little bit, and once that happens you should hit the side of the block causing Luigi to slow down right away making it easier to grab the mushroom.

Here's the video, if you are confused about what I'm trying to say.

Hmmm, I will have to try it to see how much harder it is, and if it is worth it for the risk of putting in a run at this stage of speedruning with Luigi(many “easy, not so easy” improvements) I found a 7-2 place that save a little time, but it is very easy to pull off. Great job!

Yeah, it's not easy to do since you only have like a two frame window to stomp on the koopa while also able to hit the block, and the fact that you have to switch to R and L to not bump into the block. Also thanks!