Ok i think i finnaly found a decent amp at a good price, just wondering if it is too much for my system or do i need less?

2 12" 1200W Infinities 300W RMS 4 OHM
Rockford Fosgate Punch 900-Watt Mono MOSFET Amplifier with Variable Crossover

Model: 301M
Noise-killing differential inputs eliminate 80% of ground loop noise between head unit and amp

Advanced protection circuitry monitors temperature, voltage, current and impedance and provides "intelligent" shutdown protection

Preamp and speaker-level input
- 900W peak power @ 2 ohms
- 300W RMS (continuous) x 1 @ 2 ohms
-150W RMS (continuous) x 1 @ 4 ohms
Mono output
MOSFET circuitry delivers clean high power with minimal heat dispersion
Switchable 50Hz low-pass/250Hz high-pass crossover, 12dB/octave
Switchable Punch Bass (0, +6, +12dB boost) at 45Hz
Trans-ana circuit design keeps voltages low and signal paths simple in the pre-amp section for minimum distortion and maximum musicality

Product Details

Fan Cooled No
High-Pass Filter No
Low-Pass Filter Variable (50-250Hz)
Max Power Watts per Channel (2 Ohms) 900
Max Power Watts per Channel (4 Ohms) Not provided
Max Power Watts per Channel (4 Ohms Bridged) Not provided Line-Level Input Yes
Number of Channels 1 (mono amplifier)
1 Ohm Stable No
Passthrough No
Speaker-Level Input Yes
Signal-to-Noise Ratio Not provided
Tri-Mode No
Crossover Variable (50-250Hz)
Crossover Frequency Range 50-250Hz
Continuous Watts Bridged Mono amp
Continuous Watts per Channel (4 Ohms) 150
Continuous Watts per Channel (2 Ohms) 300
Amplifier Class and Type Not provided
Bass Boost Selectable (0dB, 6dB, 12dB)
Bridgeable No

 

From those specs, you can figure approx:
75w x 1 @ 8ohm
150w x 1 @ 4ohm
300w x 1 @ 2ohm

Since you got 2 4 ohm subs, you have 2 choices:
<li>2 ohms (2 subs parallel) = 150 w each sub
<li>8 ohms (2 subs series) = 38.5 w each sub

Series is out, so parallel is a must. You'll be running each sub at approx 150 watts RMS. You'll be running them half of their max power at 150w. I suggest more power. The closer to 300w the better.

Also, Ignore peak power numbers!

 

I thought fosgates were under rated

 

Ever since best buy picked up selling fosgate, i've lost my respect for their product.

OLD fosgate amps would slam like an amp with twice the output, the new ones sound like crap and they sell them using made up MAX power numbers. Always buy your amps by the RMS number.