Best testosterone booster?

Options
Hiya folks,

Whenever I've had a hard work out day, i always feel my testy levels drop. I'm wondering what is the best test booster?

I'm taking ZMA before I go to bed, and I'm having pleasent dreams and getting good sleep but was wondering what is the best thing to take during the day?

I've tried Holland And Barrets own brand of Tribulus, but it doesn't really seem to make a difference.

Anything potent I could try?

Cheers.