From what my customers tell me and the logs on here say, DIESEL TEST Procycle is the best, single product (formula) booster avail., people won't tell you that use, it but tons of reps and etc do. Its only cool to openly speak about the popular brands, but test boosters is one thing that separate the real from the fake. The thing about the test booster market is you can't just throw some caffeine or beta alanine in a test booster and people feel like its doing something because your face itches.
One of best that is legal outside the US (as in no DHEA or yohimbe) is Diesel Test Hardcore, which has been logged on here for over 10 years.
The only other ingredients that I know of that work for some stand alone but very well with herbal test boosters are Long Jack and Bulbaine(?). People take DTH with Bulbaine. The only problem with Bulbaine is the supply is very wishy washy like Fadigoa. Trust me, DIESEL TEST came out in 2005, in 11 yrs if something new came out that worked really well (legal and natural test elevation), it would be in my test boosters. I was the first to put LJ100 in test booster formulas way back in like 2006. I had LJ100 in the original ready4war caps in 2007. It has had a re-resurgence but been around for years. It def has to be cycled, a few days on, a few off etc.
The people out there getting PCT blood work done, and actually felling like punching a wall will let you know if a test booster work for them. Also its not cheap to make good test boosters. Never will a good test booster cost under $30. Never seen it.