Aftermarket stereos...Help Please!

Ok, i know i am in for a hell of a ride here, but i'm gonna try my best to add to my audi w/the system i already own...i have a 98 a4 2.8 quattro w/delta system and bose amp...now, i know that i can't just swap out the factory deck for a new aftermarket one because the bose amp is all set for the speakers and the ohms would be all f'ed up...now, does anybody have any info as to what they did to their sound system? Also, i have an eq that would need to be mounted somewhere, has anyone found a good place for it? underneath the deck would be ok if the wood grain was cut out as long as there's nothing behind there...any suggestions???

I have the 9 speaker 150watts Bose audio system in my A4 also. I am also interested in adding some extra thump, but i really dont want to damage anything. So if you have already added a larger sub let me know. But i really cant help you out, sorry.