definately adds to the euphoria
of the dope buzz and makes you more able to be active etc
, so does speed / adderall, so both are like turning on the tap in the bath, then adderall also stops this extra dopamine from being removed (putting in the plug) and you get flooded with yummy dopamine.
In short, it's basically a speedball. Always wise to take less dope than usual when doing this in case you get stronger gear and end up overdosing, the uppers hide it for a while and then it hits you like a truck and it's too late. Had it happen a few times, not fun.