The link to the subs don't help out with the specs. Here they are:

Power Handling

Power Handling Capacity (Peak) : 600W
Power Handling Capacity (RMS) : 200W

Thiel Small Parameters

Coil Height (Hvc) : 32.6mm
Cone Area (Sd) : 339.79 sq. cm
D.C.Coil Resistance (Re) : 3.6 ohm
Electrical Q (Qes) : 0.65
Equivalent Suspension Stiffness (Vas) : 34 liters(1.20cu.ft.)
Free Air Resonance (Fs) : 30Hz
Frequency Response : 25Hz - 1kHz
Gap Height (Hag) : 10mm
Impedance (Nominal) : 4 ohm
Inductance (Le) : 1.95mH at 1kHz (0.69mH at 20kHz)
Linear Excursion (X linear) : 11.3mm
Maximum Excursion (X peak) : 22.6mm
Mechanical Excursion (Peak-to-Peak) : 40mm
Mechanical Q (Qms) : 9.57
Sensitivity : 87 dB/W/M
Total Loudspeaker Q (Qts) : 0.61

For the amp, the more important:

150 watts RMS x 1 at 4 ohms
300 watts RMS x 1 at 2 ohms


Basically what the guy is doing with the subs is running it parallel. This is combining two subs into one so that it lowers the impedance level, giving you more out of the subs. Not to say ish about what you're getting, but I wouldn't unless it's really cheap! That setup wouldn't bump as good as you'd want. If you really like alpine amps, go for Type R's. Bumps a whole lot better. As for the amp, find something with more juice.