I have a yukon xl that i am currently upgrading the system in. Currently i put in a Kenwood DNX 5120 head unit. The front speakers were replaced with MB Quart PCE213 components. the rear door speakers are still stock. they will eventually be upgraded to ??? (any suggestions on 6.5 speakers?) the speakers are running off the factory amp. it also has a 8 inch sub in the back that runs off the same amp. my hope is that when i disconnect the sub it will provide more power to the speakers for now. Eventually i will put in a JL 300/4. my goal with this build is to make it sound clean and high def. I am now upgrading the subwoofer. im pretty sure im going to go with a jl10w3 and a jl 250/1. (i have a chance to buy this set up for $150) not a bad deal seeing how its all brand new. i dont want to have over powering bass (nothing worse than a car that is all bass and no music) but i want the truck to have a full range of sound. I am unsure if is hould do a ported box or sealed. i have a bazooka tube that i was going to put the jl in. It comes in a sealed box though so i will have the option for both. i like the bazooka tube because its different and easy to take out when i need the cargo space free but ultimately it comes down to which will sound better. what do you guys think?