You need to normalize SV since bpm changes SV, but you need to make sure you normalize with the final drain time to get the correct reference bpm, so put random temporary objects throughout and exit the editor, take note of the bpm in parenthesis, this is your reference bpm
then you use math to find SV for every section - (the reference bpm) / the sections bpm = SV multiplier
assuming the number that will be in parenthesis once the whole song is mapped is 172bpm since you say only the intro is 100bpm, then to normalize you will need to speed up the 100bpm section's SV:
172/100 = 1.72
this wont fix the problem right away (it will all look like 1.72 speed), but once you've mapped enough of the 172bpm section it will be as if all SV is 1.0x