I have a 05 liberty want to get a shallow mount sub and was gonna try out a MB Quart RLP-304 {yes prolly cheap} and it is dual 4 ohm with 350 watt rms. Also has any1 every heard a shallow mont sub. Do they achieve equally deep bass as a regular sub. I have owned a rockford fosgate p2 and a orion xtr pro and i was lookin for a cheap shallow mount sub. If i have one dual 4 ohm amp do i want a two channel amp bridged to be 8 ohms or a monoblock amp at 2ohms. i dont wanna hurt the amp or speaker. Also what size amp would be optimal, im new to all of this btw. so please forgive my stupidity

 

Dual 4 ohm sub can be wired to either either 8 ohms or 2 ohm, the 2 ohm would be prefered. The amp you would want is an amp that can do around 350 watts rated rms at 2 ohms.

here is a few, also, you might be able to get a used mono amp for a reasonable price, check out for sale sections.
MB Quart FX1.400 (fx1400) 400W RMS 1-Channel Monoblock Formula

Rockford Fosgate P400-1 Mono Subwoofer Amplifiers at Onlinecarstereo.com