To be honest I prefer having them decay and speed multiply by 1.75. The first because in ASB pokemon tend to last for a while and you have the potential to turn a problem into...another problem. The second because it's close to reality. A 80 speed mon with max EVs with +1speed is faster than a 120 mon with max EVs. I am too lazy to give actual calcs here, but if you just stick with raw 80*1.5=120 math, you will end up with an underpowered boost that isn't what happens in-game. Remember that, unlike in-game, you can't just sweep with extra speed. Its good, yeah, but not that good. As for just sticking the boost in the BAP, I am all for it, as long as you just make it +1.5 always, so it goes from +1 to +3.375. If you just say its an additional rank, there is a big chance you will pass through rank 5 and end up with an actually weaker boost ._. .