I've combined clen WITH an NYC stack (Norephedrine, tohimbe hcl, caffiene) with great results... No problems whatsoever... Reason being that Clen is a selective beta2 adrenergic receptor agonist. Ephedrine is a general beta adrenergic receptor agonist meaning it stimulates all 3 beta adrenergic receptors esspecially the beta3. This is something clen can't do and studies show that beta3 receptors can't uncouple form thier G-proteins or what most people call (down regulate). Beta2 down regulate very quickly which is why you have to cycle clen in bursts. This means that ephedrine provides continual agonism of beta receptors meaning lipolosys is continual while on ephedrine....
That's how it was explained to me...
YUM