I don't know too much about Anavar and stamina increase. It could increase Red Blood Cell count (I think soomeone mentioned this as a side effect). I am doing more research as I am interested in using it.
One substance that does increase RBCs is EPO. EPO is a hormone from the kidneys that stimulates your bone marrow to make more RBCs. It is the stuff pro bikers use. It will definitely and significantly increase endurance. However it can be dangerous if not used correctly (you need to hydrate well and take blood thinners).
Salbutamol is asthma medication (inhaler) and will open up the aveoli in your lungs allowing you to take in more oxygen. It won't significantly improve stamina or endurance, but it will help some.
I don't like ECA as a pre exercise supp. It will definitely help give you a boost, but it can't be regulated (except by changing the dosage you take). The long term sides are really shitty too. I know guys who've developed heart problems from too much ephedrine. It is a bronchodilator. It did a post on this stuff and cardio and why you should avoid it. Do a search under my name.
FHG43