Alternate defrosting for a 914?

[jzglinicki]

Looking through the Pennsylvania vehicle code, we're required to maintain working defrosters for street-driven vehicles in this state. Unfortunately, every performance-oriented exhaust I've seen has no heater boxes.

Does anyone have suggestions for alternatives, either a good exhaust with heater boxes (that would still support 150 hp or more) or a different type of defroster?

I think the old VWs used some kind of a heater that sat in the front trunk and used fuel from the gas tank, but I know nothing about them. Anyone know anything about them and have any suggestions on whether such a thing might be fitted easily to a 914?

Thanks!
Joe