Test boosters do precisely nothing for gainz. If there was anything you could just buy over the counter that would make a meaningful difference to your hormonal profile then all your pro sportspeople and bodybuilders would be using it... but no, if you want surpaphysiological levels of testosterone then you have to get used to being a human pin cushion and use substances we're not permitted to discuss on here.
If you think your test is low then you should be looking at addressing the things that can cause low T and getting your levels checked. If you want to high enough T levels to make rapid gains...