From the N0 W4RN1NG ope potentiation thread:

DXM (Dextromethorphan HBr, Robitussin, Zicam, etc.[not that it needed an intro on this board]) has a special effect in this formula. Although it doesn't inhibit the CYP450 set to any appreciable extent, it does contribute to analgesia and euphoria for all major opiates. Also, it has been shown to prevent the build up of tolerance! 30mg of DXM a good half hour or so before dosing will definitely slow any tolerance build up if you use this method every time. And with opiates, that's a VERY big deal.

OK, so according to this, DXM slows down an ope tolerance buildup. But this 30mgs of DXM is a part of the potentiation formula. However, if a recreational user were to take around say 20mgs DXM every day, would this keep tolerance as low as possible? Or would taking DXM daily make no difference to tolerance effects?