Pain is typical of very strong test. It is called PIP (post injection pain), and can be expected from potent test. You can google post injection pain and research it. That is actually a testament to how potent it is. Painful test comes because it is so saturated with testosterone, that is crystallizes in your muscle when it is injected. Your body then sees it as a foreign substance, and attacks the crystallization. This causes swelling, a hard lump, redness, and pain. You can also get flu like symptoms from this, which is called test flu. The more saturated with testosterone, the more it hurts. It is actually a sign that it is very strong test. Here is how to fix the PIP: You can mix it in the same syringe as your tren ace. This will dilute the test 400, making it more soluble and less likely to crystallize in your muscle. If this doesn't help as much as needed, get some grape seed oil and add that at a 1:1 ratio or less in the same syringe as the t400. This should now reduce or eliminate the PIP.