I have JL comps in the front location, a JL 2 way in the rear location and a 8 in JL sub in the stock location. Ran by 2 amps. One for the door speakers and 1 for the sub. It all helped but the biggest improvement came from deadening the car. Once I made the doors and stock sub location solid the mid low end really came through.

 

Thanks guys

 

i had an 05 cobalt with the pioneer system and it sounded great but the hhr's system im guessing is different cause my dads (2LT) pioneer doesnt sound that much better then mine and i dont have pioneer

 

I cannot see any reason to upgrade to the Pioneer system. I have it, and its junk. I am currently in the process of upgrading my system. After pulling the door speakers, they are the good ole wizzer paper cone speakers (I thought it was a "premium" system) Hell the car is only 2 years old, and the drivers side door speaker already had ripped at the seam attaching the cone to the frame. I am going to attempt to use the factory amp for the door speakers and see how it sounds with some efficient Boston Acoustic speakers, but I would not be suprised If I have to replace that as well. The sub really confuses me. They only way you can get any noticable output is to move the fader towards the rear speakers and then turn up the volume. I don't understand why the GM engineers designed it this way. It should have had a seperate adjustment for the sub. Buy yourself a decent aftermarket CD player some coaxial speakers and nice sub and forget about the Pioneer Premium system.

 

replaced the doors w/infinity refrence 6.5 speakers dynamated front & rear what a sound differnce to the stock sound!
2 kicker amps and 2 12" Kicker Shallow subs custom mounted above the amps w/ an autobot logo etched on the top in the Pleather sounds amazing.no premium system for me ive been transformed and upgraded pics in sub enclosures soon.
Dynamat makes all the difference!