Meth is only slightly powerful at releasing NE and DA, it is potency comes from its solubility in fatty tissues.
NE release DA release SERT release
EC 50 (nM ± SD) EC 50 (nM ± SD) EC 50 (nM ± SD)
(+)-Amphetamine 7.07 ± 0.95 - 24.8 ± 3.5 - 1,765 ± 94
(+)-Methamphetamine 12.3 ± 0.7 - 24.5 ± 2.1 - 736 ± 45
As you can see amphetamine is active an mM range, this means you need a very big dose to induce release of SERT, meth on the other hand is 2.5 time potent and it is very likely that recreational doses will elevate serotonine levels.
As for the dose - I cannot answer you, maybe more educated person will.