Ok so I have tried a quite a few and the best one I found was DIESEL TEST LIMITED EDITION by GET DIESEL NUTRITION. It is all herbal and helps with many things I.e. strength gains, fat burning, energy, aggression, motivation, performance enhancement, and libido. Even though I know you said that's not important. It is not a well known product but it works. Check out getdieslnutition.com or just Google diesel test limited edition. I like to stack it with D-pol a d-aspartic acid product. He also makes a stronger version called diesel test pro-cycle but I did not like it because it contains yohimbe which makes me nautious. Also yes there are many people who say test boosters don't work but I have faith in the diesel nutrition products. As for tribulus, it doesn't do anything to raise test levels but will raise you're libido. It is in these products, however. Last of all blood work is the only way to know the truth about your test levels. If you can afford to get your blood checked before and after using test booster products. Get your free and total testosterone levels checked. Either your Dr can do it or you can order kits online. Hope this helps.