alright i got 2 Jensen 10"s in a bandpass box that were made for them, a pair of Pioneer 6.5's in the front, a pair of pioneer 4way 6x9's in the back. the interior speakers will be powered by a Alpine MRP-F240 40W x 4 Car Amplifier and the subs are powered by a Profile CA400 100W x 2 Car Amp. The head unit is This one

i have all this stuff im just waiting to get my .5 farad cap and my 2 wiring kits. im wondering if you guys think this is a decent setup for a s4 GXL or is it gonna sound like complete ****. and i plan on swapping the jensen subs for alpine type s's soon.

 

That is a killer head unit. If done right it can sound pretty decent.

 

should i use 8gauge or 4 gauge wiring?

 

IMO, I always say go with bigger. It gives you headroom if later on you decide to upgrade to more power. Saves you the hassle of re-running your power wire.