one thing about quads is to hit it as far outside as possible, like where your pantseam line is...go in dead sideways and you will have better luck, but i still got a few bad shots in this area.
lat injections made me cramp up too much. for some reason my lats are very sensitive and when i pin there they will cramp up like crazy for a few days. i only did it twice in each lat and i'll never do it again.