well, nothing is for free. You will put more strain on it iof you drive it like you stole it everywhere.
you are looking sub 200 BHP on chipped power. Best bang for buck you can do.
AS for the mileage, mine has over 140k on it and i am looking at big turboing it at some point. I have however changed oil pump, and put upgraded rods inside to see if i can help it remain together