I am not a heavy stim user so keep these suggestions in mind...
Want super heavy stim and don't mind Rauwolscine? Check out Muscle Addiction Pump Addict Ultra Hardcore. The pump and stim blends would be pretty solid even alone.
Don't want Rauwolscine? Maybe check out Gorilla Mind Gorilla Mode.
Want caps? SNS Vasoforce Rush.
I am sure there are others and the stim heads around here can probably point you in a good direction for the stim side of things.
If you don't mind combining things then find a stim you like (or someone else can suggest) and combine with CEL Superswole, SNS Vasoforce, Pescience High Volume or Proccor Ultra Octane, these are my current favorites for pumps and performance.