Exhaust questions

[Liv4Lax11]

If i install a new exhaust system what will it do for my gas milage numbers? Also is it much louder than the stock? Also what is the hp gain with it? If i do end up doin this which one should i get.

[AKLGT]

I would suggest making use of the wonderful SEARCH function and look up exhaust. there are tons of threads w/ all kinds of info about this. just like anything, they are not all the same. depending on what your likes and dislikes are, your best option is just do some research and see what you think will fit you best.