Booster question

It's still a +3 boost at level 15 right?

I just tested lv14 and lv15 Booster, there seems to be somewhat of an increase at lv15. But I can't say 100% sure, because it doesn't even say the speed increase in the description. My friend also just said lv15 felt faster too, so yea.

I just tested lv14 and lv15 Booster, there seems to be somewhat of an increase at lv15. But I can't say 100% sure, because it doesn't even say the speed increase in the description. My friend also just said lv15 felt faster too, so yea.

Level 14 is -2 and level 15 is -3. So, yes, there's a definite increase in speed.