Engines are a couple of TDI's small turbojets, either J85s (200 lbf) or J7 (70lbf). That's not a lot of thrust.
The unusual number of engines may be simply due to the fact that there are so few small turbojets that in order to get your right amount of thrust you need more than one. For example, i don't think there is much available between 200 and 600 lbf, so if you need 400 lbf, voila, you use two J85s.
Also, as pointed out, i don't see any attempt at area ruling. I think this is firmly subsonic.