I know enough not to start a electric fire....

What car?

What speakers did you buy?

Rear speakers could still be trash. If you didn't solder the speaker wire, you could have a bad connection.

Unless you have a really quiet high end car, I've never been a huge fan of throwing lots of money at car audio.

I've always let the head unit power speakers and than use a RCA sub out to a sub amp and subwoofer.

Only oddity I've ever seen is my first car 92 Escort GT, seemed to share the same ground wire for all the speakers. I ended up rewiring everything.

Sorry for not making it clear, but this is for the gvr4.

Rear speakers are stock.
Front have been replaced with some pioneers that I got from chucklesas' old car. No idea what model they are. Originally put the speakers in with stock head unit and still sounded "off," and it didn't change with the aftermarket HU, except for now the rear speakers work.

I can't describe what the audio sounds like, besides off. The treble and bass just don't seem to work well together. What also doesn't help is that the car is loud during hwy cruising. I am thinking some sound deadening material on the roof would help there.

If you have the factory speakers, you can be rest assured that the paper cones and surround are toast, sound will be bad.

I have not used under the seat subs before, but I'd image they would work. You will get more gain from the trunk. I have a simple sealed 10" sub in a goldwood box. Nothing fancy, but it works. I've thought about trying a slim sub in my Celica cause I don't want to add much weight or loose trunk space.

You can go smaller, but you lose efficiency. Dayton makes a 6.5 and 8" sub with matching passive radiators if you can make your own box. They also make a slim 10" sub if you could fashion a box mounted to the rear deck so you don't lose as much trunk space. Tang Bang make some nice mini subs too. click

There are many very competitive car audio components that can be had for really low prices, with the right know how and searching. This site will awaken you to the world of car audio DIY, and has very VERY tech savvy members to boot. Figure out your budget, and see what used components are being offered and the go hunting. There are tweeters in the $29 range that will sound nearly as good as $200 tweeters to most peoples ears, and with a great head unit (CD or digital audio or both), will get you into those heavenly sounds that area usually only associated with home audio. You can get a car sounding great with little work other than proper placement, good equipment and some tweaking of the crossovers (going active). I have only installed my tweeters and 6.5" mid bass speakers, using the source signal of a Pioneer Carrozeria P-01 JDM head unit to the P01 JDM six channel single din amp in a stacked formation, and I am already in auditory heaven. I still have 2.5" mid range speakers waiting to be installed to take over the middle spread and open up the top end the 6.5" speakers weren't meant to complete deal with but are doing an admirable job considering positioning down low. In the trunk should be a giant fuzzy, reinforced box housing one 12" sub. This sound system is strictly for SQ and not SPL. I have spent nearly a year dealing with acquisition and prep, and build and then installation. I have had my lower dash apart for the last 2 months. This is in a car that is different from the Galant, but as the guys have said, remove the drone, dampen a little, get rid of rattles with anti-squeak tape sticky backed foam tape from 3m, and so on. The more quiet your car is to start with, the less you have to overcome with audio, and the rest will shine with a little tweaking. If you add more volume to compensate for the exhaust and lack of interior damping, you start the viscous circle.

click

Your plunge into the rabbit hole begins now .........