Putting a system in a denali

I have a friend of mine with a Denali, mostly stock on 22's and tvs xbox and whatever but Ive got her interested in putting at least 2 12 inch subs in there for a little bass...she was tellin me that she has heard that putting a system in a Denali will mess up the factory BOSE speakers and seeing that i have no experience with a Denali, was wonderin if anyone knew if an added 2 subs and amp will mess the factory BOSE up, thanks for the help in advance.