WonderMelon, try soaking a little lacquer thinner or Goof Off on the glue. Test a little spot first.

As far as the impedance I'm going to replace the stock amp as it sounds pretty bad. I've tried it with each of my Alpine CDA-7897 and CDA-9855. They sound much better than the stock radio but the amp still sounds bad. There's some kind of limiter too in the amp that clamps the signal when I try to use the EQ and MX features in the Alpines. The stock amp has a 15 amp fuse so it's probably only 150 watts total output or less hence the need for the low 1 ohm impedance of the stock subs.

Power amps are cheap and Class D sounds better than it did 10 years ago.
Look at this amp dyno of this little monster from Kenwood.

95 bucks on amazon