Well it really depends on the ammount of Benzyl Alcohol in the prop to keep it suspended. So far, Pinnacle's test prop has been almost completely 100% painless. I use both quads and my glutes for injection sites, and have not had a single problem. Also, Biogenetix labs test prop is like injecting nothing. Cant feel a damn thing and great gains. A very small lab that you can find if you look hard enough, Zeus Juice, has also been painless and extremely potent, at least from the gains I have seen using it. For some reason, Sciroxx hurt like a motherfucker. It was dosed right, but still hurt like none other