Modern Vespa

I have what amounts to 17.5 gm Dr Pulley sliders in my variator which I consider the best balance between revving, take offs and gas mileage. I've noticed in a casual way that the engine braking is improved with the lighter rollers which is kinda counter-intuitive to me but much appreciated. Today I went exploring and went up some really steep twisty roads (residential no less!) with equally steep down with some curves marked 15 and 20 on a steep grade. The engine braking was MUCHO appreciated there.
Now the real surprise came when I found myself next to a gravel operation. I looked at the road carefully and no gravel was on the roads. But there was thick heavy white dust in the air which I made the mistake of dismissing. That shit was on the road and made it like oil in the curve - I started a 3 wheel slide - nothing was grabbing; sorta like Fast-n-Furious drifting. I confess it really surprised me as the dust wasn't what I would call visible on the road. Anyway - by instinct I backed off the throttle sharply which is an old dirtbike trick to do a weight transfer to the front and straighten you up a bit. It worked! I actually had enough engine braking to make a difference when I backed off the throttle. So - just an FYI that there are other advantages to putting in some lighter weights besides go-faster.

I put 16g Dr Pulley sliders on my 400. I have also noticed increased engine braking - particularly that the braking lasts almost to the end as I slow to a stop. I think the lighter weight keeps them engaged longer. They also engage almost immediately when I start off from a stop.

(I don't know if anything actually mechanically "engages", but it does feel that way.)

I note better engine braking on the Costa as well, though it is not much compared to most things, I am happy for what I can get around these mountains here. I have had the Pulleys, though heavier ones. It might be worth looking at those 17.5s at some point, as the more Engine braking the better, particularly since we can't shift down on our scoots.
I am amazed you can find such steep downhills in Austin and the Hill country ( and once you even mentioned 10 mph switchbacks--but I assumed you were off your meds that day).
That three wheel slide must have been a big surprise--think you would have went down on two wheels?

LOL - c'mon - what makes you think there wouldn't be 10 mph switchbacks here? Plenty of hills and some of 'em pretty steep - they just don't go all that far up - or down.
No - it was the same kind of slide. The MP3 will save you if it's in patches. You're mostly in the same boat as a 2 wheeler if all of 'em can't find traction.

10 mph switchbacks are not all that common HERE. But if you see one, best to pay attention--means what it says!

Don't need mountains or even hills for 10 mph switchback. I south east Arkansas any thing a rabbit can't see over is a big hill. HWY 7 in south Arkansas is a flat as it gets and has some 10 mph switchbacks. Either contractor who laid it out was drunk or paid by the mile so he added some. Another theory is he started surveying it where it starts near Missouri and by the time he got out of the Ozark and Ouachita mountains he was in the habit of putting in a sharp turn every few hundred yards.