If you don't dilute a highly concentrated mix with carrier oil, you will generally feel some post injection pain. In some cases it will be so severe that you won't be able to workout that muscle you injected into. You've been warned, lol.
Been in the game +6 years as a source. My experience is saying that never use mixes. They are mostly low dose stuff. Make your mix/stack by yourself. For test p mast p tren a, don't buy mix that claims containing all 3. Just buy 3 of em each.