All the usual cacti species vary considerably in content, from species, to time of harvest, and many other variables. Therefore you will not have much joy making a definitive rule for this I'm afraid. Lots of literature says T.peruvianus is higher than T.pachanoi however this is not always the case. Basically stuff varies, I would opt for a species with a more reliable knowledgebase tan Terscheckii. Check www.erowid.org for more information You are young also, I'd wait sometime...and approach it with a few more years under your belt.
