[Gen 3] New catalytic converter on my 08 auto, less eager downshifting?

Hi all. I had my catalytic converter replaced a few weeks ago due to rust and degradation. With the new one I've noticed 2 things. Firstly is that I get a different vibration feeling at certain revs (not bad, just different) but secondly my Jimny now seems less keen to downshift unless I mash the accelerator.

Is the latter a sign of anything bad like impeded exhaust flow (or indeed the opposite, improved flow)? I don't think the performance is noticeably worse or better but the downshifting I find interesting. Is there some kind of feedback from the exhaust O2 sensor that might have changed this behaviour? I don't really mind the way it now behaves, in fact I prefer the downshift not kicking in unless I am really asking for it.

Sorry if it's a question with an obvious answer! In my head the story goes something like "old cat was impeding exhaust airflow, this meant the engine was less performant / weaker for a given throttle position, this meant it wanted to downshift sooner for the mechanical advantage". Anything to it?

It could be that there is less restriction, so you don't press the accelerator as far down, so the downshifting happens at a lower speed.

It should go from 3 -> 2 at 46mph with your foot on the floor, but waits until 8mph with the throttle closed and coasting to a stop.

i have a manual but for me after changing my constricted cat, going uphill from the bottom of a local undersea tunnel, (-287m and up to +10 with a 9.6% hill) , I went from doing it in third at high revs and just barely making 80kmh to having to release the throttle to avoid loosing my license at 120kmh in fifth gear.

So yes it just might be your new cat but you will not notice it much driving in the flatlands.

The vibes might be the added mmpfh