You can use regular amphetamine, such as racemic street amphetamine in which a acetone wash will provide you with higher quality substance which you can use.
You could also go the route of
>>12598435, and use Dextro / D-Amp, but finding d-amp on the street is more difficult than just illicitly purchasing Dexedrine or whatever equivalent is within your country.
Depending on where you live, getting a diagnosis can be easy and used to obtain high grade stimualants, namely Adderall(75/%25% Dextro to Levo, amphetamine).
Or supposedly better Vyvanse / Elvanse, which is dextroamphetamine but with Lysine attached to it so that it lasts longer and is smoother.
Another potential route is buying and using various Research Chemical stimulants which may have more favourable properties for a given activity.
Derivatives of amphetamine such as 4-FA, 2-FA and 4-FMA may be useful for increased attention without the euphoria of traditional amphetamines.
As well as potentially using phenidates, either standard methylphenidate(Ritalin) or any derivative of it such as 4-MPH, Ethylphenidate or Isopropylphenidate.
