Well first of all, the actual question is moot. I'm sorry but you bought the equipment. If you were not able to try it or get an honest review about it first, you honestly get what you pay for. Just a little research is all it takes; so in asking will it sound good; you should already know your answer. Besides, what sounds good to you may not sound as good to someone else- there are too many variables to take into consideration with a question so general. Not only product, but also, vehicle, install, power, frequency cut offs, positioning, dampening, location, etc.
Volfenhag's Sub
Pyramids Sub
Kinda look similar dont they.....
We all know the capabilities of Pyramid arent so impressive.
I would also question the Legacy Amp a little, I have wintessed and saw several cases where they have dont more damage than good to a system. Really though, as long as you keep the Legacy at or above 4 ohms and mind the gains, you shouldnt have too much trouble.
The rest of the system is well thought out and quite capable of sounding excellent, again, depending on the factors above though.
One thing I picked up right away is that even the best speaker in a poor install can sound bad, yet a lower end speaker in it's proper install can sound pristine...
Good Luck!
-zane