2000 Sunfire GT Audio problem.

[johnmk]

I just installed 2 pairs of JBL speakers into my car. Everything is great as long as it plays low, when you add more volume my radio just does not have enough power and base fades away...
I was thinking of buying an aftermarket audio deck, and was told, that from year 2000 all Sunfires contain computer (aka central processing unit, aka “furnace”?) build into the factory radio.
Another words, I have to replace not only my radio, but a computer as well? Furnace at BestBuy costs around 150 + installation.

My friends are telling me that it is bull and my computer is under the steering wheel. There are bunch of relays under the drivers side panel, but I am not sure.

Anyone has any experience with it?