Open Question: Okay, I've read numerous reviews about all different types of pre-workout formulas for working out at the gym.?

I want a good N.O. booster. I've tried NO Xplode and Jack3d. Both have done well for me, but there's a lot out there about magnesium overdose, etc. with the NO Xplode. Can anyone out there actually give me their honest opinion about the best NO formula to use. I'm turning 45 years old and I've been working out for a while and am muscular. Just need to try something different (I think).