moon and tune, what type amp is it??

[04vibeman]

I have never altered my 2004 Pontiac vibe in anyway since it was purchased. When i bought it, i got the package that involved 6 speakers and an amp (along with a moon roof), called the "Moon and Tune." Now i want to put a MTX Thunder4500 T4510-04 subwoofer in it. Its a 10" 4-ohm. My problem is i don't know if the amp that came in the package is 8 or 4 ohm. Does anyone know if this subwoofer will work in my vibe, (if not any recommendation to what would)(i'm on an extremely tight budget)