i've got an ht3e in my set up. it's just a slightly smaller turbo all the way around (turbine, compressor, housings). quick spooling, maybe not the best for flow? i think if you were to w'gate the bejeesus out of both of them, you'd be fine, depending on what your goal is. i can't give you a whole lot more info as i don't really have mine tuned yet and i need to get at least one 'gate on there. the highest boost i've seen so far is 53 psi. i've just got a hybrid on top. at low to mid rpm's the drive pressure is 1:1, but once it gets past about 2200 rpm, dp goes WAY up. you NEED to wg the set up. i've got a bunch of pics in my readers rigs of the build up if'n you need something to look at.
dave