Well i can say from what i know, with me i say its 60mg IR, XR i always figured go up 20 mg but don't quote me on that, i love the effect from amphs but, i tell you what, to me thats a 1 to 2 day deal then wait a month, your tolerance IMMEDIATELY goes up i do believe, feels like it anyway, but you can't go by me, my brain is pretty messed up because i was hooked on opiates for 9 years, stimulants i have been doing for fun since i was 12, im 27 now, but one thing i must warn y'all of is even though it's not my drug of choice, it takes ALOT of control to not binge, its not worth it because then it's all just negative effects afterwards, also the comedown is depressed city, anxiety, all that fun shit. I would never go over 60 mg IR, IT'S Pointless, no higher plane for the euphoria, i binged on vivanse for 5 days, started 60 mg, was doing almost 300 the 5th day, it was PURE HELL so plz ppl, don't go over 60, you will achieve NOTHING