i've done some crazy things when combining benzos with amphetamines.
as christ! says - they lower your inhibitions, and this can be a very dangerous thing when those inhibitions are there for good reason.
there is something about the loss of control that benzos (especially in combination - with alcohol particularly) that makes you feel completely normal - even straight - but you only realise in hindsight that you realise how out of control you were.
you feel calm...relaxed, but you're not in control. the barriers we impose on ourselves drop - and this can lead to all kinds of risky behaviours.
after your "i shit my pants" thread, i'm kinda surprised that you started this thread.
if you don't learn from those kind of mistakes, it is very likely you will come to some considerable harm, or find yourself ostracised.
it's kind of crossing over from "silly trashbag" antics to "disturbing lost cause" territory. and i don't mean to judge you, but what you're talking about is really irresponsible. if i were you i'd be reassessing the combination, not thinking of ways to increase it.
you might feel invincible (especially when you take benzodiazepines) but the risk of respiratory depression from opiates in massively enhanced by mixing them with benzos.
after you pass out and puke/shit on yourself in a public place, you want to up the stakes? i do hope you see the foolishness of that.