I feel your pain man
The bose system has a really nice low note that I have not been ablt to reproduce up until recently.... They balance their systems very well and I love the look, the sound, and most of all the steering wheel controls.
My first attempt was pioneer deck and JBL 6.5s and 6x9s, non amplified. Had everything but the low bass.
Second attempt was Alpine deck, kicker 6x9s, JL 6.5s and a sweet phoenix gold amp hoooked up to the 6x9s. They cranked, but still lacked the low bass.
Then just on wednesday, I swapped the phoenix gold amp for an older pioneer premier amp that was attatched to a sub that I am selling.
This turned out to be succesful because the amp was more tweakable than the phoenix gold was. You could adjust bass boost, and the HPF filtere crossover frq., and a few other things.
So now I have the deep bose bass, but I think you can only get it with the right combination. You need to amplify aftermarket 6x9s, with the right amp, and you will get it.
I dont think you can do it by just replacing the speakers...
I miss bose anyways