Factory bose help 97 sts

I have a 97 sts caddy,I want to add some bass and an ipod interface to the factory sys.I have read many conflicting opinions on line converters and integration products that are out there for these premium systems.If you have experience in this area please steer me in the right direction.I have a few questions on specifics of installation of line converters,is it better to tap the speaker wire before the amps or after them?what is the best place to land the remote amp turn on wire?will the ipod interface work with a sys that has a cd changer in the trunk(dont need it anymore but wonder if the hu has a coresponding connector there?).
And a final question,do you know of another route that would be more suitable than my idea of using line converters, ie a product that wires to hu and will give me a cleaner signal?