I've tried dozens, only one works for me. Dymatize Xtreme Pump. They discontinued it, so I ordered 3 tubs. When I ran out before, I ordered Buzz Saw from truenutrition.com. That shit makes me sweat so much it's embarrassing. I sweat a fair amount normally, but after drinking this, sweat is dripping constantly onto the floor...
Just cracked open my first tub of the Dymatize, and had an excellent work out.
Stacking pre-workout drinks is a terrible idea. I'm surprised people would even consider doing this. You're OD'ing on not only caffeine, but if you consume too much arginine and NO, your blood pressure can actually drop to severely low levels and become life threatening. It's happened to me before... got an adverse reaction to NO Xplode..nausea, dizziness, blurred vision, and a headache in the back of your head are the symptoms of it.
Stick to one mix. If it doesn't give you what you're looking for, try another product! Plenty of online stores have samples you can get.
I think the biggest problem with these products is that none of them list actual dosages for EVERY ingredient... 'proprietary blend' is just a bunch of BS if you ask me. I'd like to know how much of each ingredient I'm consuming, especially caffeine.