it is supposed to increase the signal to like 8v. thinking of getting one when i do my system because i'm keeping the head unit. and i know they use this converter that is pretty crappy so you would need a high power amp.
btw, here is what i plan to do (as soon as i get some money), tell me what you guys think. front speakers focal polykevlar 165k2, either an alumapro alchemy 10" dvc or jl audio 10w7 for a sub, and for amps a phoenix gold 475ti to run the fronts, and 600ti for the rear. i'm going for sound quality rather than spl.

 

keeping the stock head unit? But buying 500 hundred dollar subs? get a head unit, you will never get the sound you want out of that stock Hu...

 

$500 sub. you're getting ripped off.