When I switch my p1s from regular mode to sport mode, the printing gets very choppy. See attached photo with the part circled that was printed in sport mode. I worry this could even damage the nozzle when it gets back to the choppy part after it hardens. I wont even think about ludicrous mode. Anyone else have this issue? Edit: just regular Bambu PLA
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this is not a printer related issue. I printed models in sports mode and even in ludicrous mode. there are a lot of things which will prevent printing successfully in one of the higher modes. here are a few things I figured out during the time:
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use DRY filament
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use calibrated or bambu-filament
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use a CLEAN print bed
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calibrate your printer
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do NOT use the hardened steel nozzle as the quality gets poor with higher speeds
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do NOT expect that all models work with the same mode
I switched to a CHT nozzle a while ago and have printed a lot of models with 124% speed without any issues. when I had failures most of the time the filament was not supporting higher speeds and tended to loose quality. I never had problems with bambu filament or similar quality filaments (using bambu-profiles). Sometimes prints failed due to less adhesion so I cleaned my printbed before each print. Some models had less adhesion as the profile was not using a brim and when the printer started to move the model lost adhesion and was gone. …so in one sentence - most of the models can be printed with higher speeds but you need to eliminate my list in order to finish your print successfully.
EDIT: related to your current issue → I would try to dry your filament for at least 8h in your printer / in a filament dryer
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Sport and ludicrous mode aren’t magic. They only apply a multiplier to the speeds. This may work in some cases, and in others it won’t. A lot of printers had that feature before even though it didn’t have a name. On my old Artillery Sidewinder from 5 years ago I could increase the speed 4X by just using the touch screen if I wanted to get shitty results. 
When it doesn’t automagically work, it means you’re gonna have to put in a little bit of work to get the extra speed you want. Start by increasing the flow rate and temp in the filament options. When the nozzle moves faster it needs to feed faster. It might not work on the first try. You’ll need to experiment and build your own experience. and do it again when you print a different color as pigments affect how a filaments flows.
As for damaging the nozzle, what do you think is tougher: metal or plastic? Worst case, the bed will flex if the nozzle has to ride over bumps.
When people say plastic can damage your nozzle they mean abrasion from melting carbon or glass filled filaments.
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You can use hardened steel nozzle at very high speeds just fine if you increase the temp. You’re only limited by how high the hot end can go. For PLA it won’t even break a sweat.
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Make sure that the thermal paste between the nozzle and the heater cartridge isn’t starting to dry out. At the higher printing speeds heat has to transfer faster and degrading thermal paste has been shown in the past to cause issues like your seeing.
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I already tried several parameters in the past but was not satisfied. Switching back to my CHT (not even steel) nozzle solved this. you are right - you can solve these issues with the parameters but I was lazy 
for me the 124% pre-setting was enough. Most of the times the filament is not dry enough (even when it comes out directly from the packaging). after drying the filament & cleaning the bed almost each model worked for me.
for example → this is one of my lamp models printed @124%
When you zoom in on the second picture → you see dust but no printing artifacts
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I think a lot of people overrate drying filaments without even measuring the humidity where they live. If a build fails they’ll be quick to say the filament wasn’t dry enough instead of checking their parameters first. You see it all the time here on the forums.
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my usual room humidity is ~56%. so there is a HUGHE difference between ~15% when it’s dry (and long time stored in the ams) and 56% lying around elsewhere. for me it’s definetly not overrated!
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I want to thank everyone for the great feedback. Since Bambu support is, ahem, overloaded at the moment, it’s great that there is such a community here. Without the community, I don’t think Bambu as a company will do very well with their current issues.
I’m thinking that the comments above about the hardened nozzle might be on to something. I’m not sure, but now that I think about it, I didn’t have these issues until I changed the nozzle to the hardened steel. When I find some time, I will change it back to see what happens. I’m not sweating the issue at the moment, as I’m not printing for commercial purposes so the speed isn’t critical. I also note that other filaments don’t have this issue, for example PLA silk and PETG usually print pretty well on the faster modes.
was it a complete hot-end with thermistor and heater or did you move the thermistor & heater from the stainless steel to the hardened one?
Generally hardenable carbon steel has a higher heat conductivity than stainless steel thus would provide a more uniform heating of the hotend therefore in theory should work better.
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I’ve had a similar issue, since the last couple updates. In my opinion I have noticed, if you change speed when it’s printing as in the extruder is on the plate extruding this will happen. I’ve noticed if you make your speed adjustments during the live print, do them while the extruder is over The Purge area.
when switching manually to sport or 166%,and ur filament flow/speed settings are not set up correctly it will fail…
Interesting, then how are you supposed to select sport or ludicrous mode initially so that the gcode sent to the printer is compatible?
Here is my five cents worth in regards to firing up the afterburners…
It WOULD be nice to be able to actually control this speed change properly and already when slicing the model.
Finding the best moment to increase the speed without causing the extrusion to go nuts for a while is a hit and miss.
I usually hit the overdrive when the first sparse infill layer is already down and right after the wall loops for the next layer were printed.
This way all extrusions issues happen in the infill which is usually not causing any visual problems later.
The .4 standard nozzle seems to work best while the hardened steel one (original Bambu) struggles to provide enough flow, especially if you dare to combine the infill layers.
However:
With an aftermarket and surprisingly cheap hotend and that hardened steel nozzle I can actually get much higher flow rates than with the originals of either type.
Having said that…
It is surprisingly hard to calibrate for those high speeds…
You can’t just ramp the speeds up manually and calibrate using test models to find what works.
Give it a try and you will get different results for a manual increase to let’s say 164% compared to pushing the button.
The slicer seems to adjust a lot of things differently to how the speed buttons and their algorithms adjust values on the fly.
A good indication of how well the buttons might work with any given filament is to do one of the max volumetric speed tests.
If this fails at 164% of the original speed you already know your prints will fail as well, or at least suffer visual imperfections or worse, adhesion problems.
Another issue I have with the speed buttons is the total lack of temp control.
If you print VERY slow you can’t extrude at excessive temperatures as it would just create a goo mess and results in very overcooked plastic.
Same the other way around - the faster you want to go the faster the hotend has to melt the plastic to the required temperature.
As the contact time is much slower you need a higher temperature.
At the current state these features are only good for certain models - like those where the machine can run with a more or less constant speed rather than having to slow down for details or when doing lots of supports.