Have you thought about going with a Meisterschaft setup? That way you dont have to think of this as wasting your money. You buy the axle back, then when you are ready to do your upgrade, you just purchase section 1, and the Y pipe. Thats how they sell 90% of their exhaust systems. If you havent heard their exhaust, heres a youtube clip for you to check out. Its really my favorite sounding exhaust thats out there.
GTHAUS Meisterschaft GTS Nissan 370Z exhaust sound - YouTube