True low pressure with a Tippmann isn't possible because it's a blowback, meaning that its firing and recocking pressures are equal and are in a straight line. Since the spring tension must be sufficiently strong to allow for an acceptable dwell time AND hold the sear all in one, it just can't allow a low firing pressure because it has no means of separating it from its cycling pressure. Were it to have a second chamber (Which would complicate the design and raise the price, which would negate two of Tippmann's supreme strong points of being cheap and simple.) for air for recocking, it would no doubt have a regulator similar to an Angel's to lower it down considerably. In essence, you would have something like a Shocker, but in a smaller package. Hrm................
In fact, almost exactly an Impulse.