okay...just wanna let ya know some stuff...you're gonna be running the subs at 1.8 ohm load...make sure the amp you get is 1 ohm stable...second...make sure you get an amp that puts out atleast 400 watts RMS at 2 ohm load...might wanna go for about 450 and not turn it up all the way...for calculating resistance i have some formulas for you...

Parallel Resistance: (R1 x R2)/(R1+R2)

Series Resistance: R1 + R2

hope that helped