Do XP boosts still stack in Preseason 8?

Yes! Actually there is an insane player on EUW who probably does not sleep and is a great example Win EXP Boosts and Day Lasting EXP Boosts as they have stacked them and played to lvl 167 (just now) with 4x EXP!!! and it seems to be as though the fastest way to earn exp is through Bots Twisted Treeline in 8 minute games won (As Jinx or Tristana bc they push fastest)!