have you tried beta-Alanine?
I have, particularly in Phosphagen Elite and Nano Vapor, and I like it.
Although, I'm beginning to think you grow a tolerance to it, after a while. I got the tingly feeling everytime I took a serving of Elite and initially every time I took one scoop of Nano Vapor (and it was several months between trying both products).
After about 2-3 months of using up my first jug of Vapor, I bought another one. But, the feel isn't quite there. Maybe I should have stuck with Fruit Punch, instead of the Blue Raspberry kind that I currently have.