just bought the Pioneer AVH-P4000DVD and was wondering how i can go about installing it without having to remove the infinity amp which i dont even know where its located. i want to place in this dvd stereo and through an old amp/subs in my trunk and hook them up to this new receiver. is it possible to do all this and also keep the stock amp hooked up to the regular speakers? and if so can i do it through wire splicing and not having to buy stuff? can someone please help?

is it even possible to do that? because im concerned if i just bypass the factory amp and the only amp i run off of is the one for my subs that the factory speakers might suck more

Get the adapter for the factory amp output,or get a different amp for your surround speakers.Yes they would not sound as good w/out it.