If an auto, I'd go with a shift kit. It won't give you horsepower, but you'll more efficiently use what you have. A chip would most likely be a waste of money, I don't think they help most stock engines much. With dual exhaust you could possibly lose some torque, you need some backpressure to a certain extent, but if you keep the pipe diameter around 2.5 iches it would help some. The headers would probably help though. Check out Steeda.com, I think they have a few parts for trucks. Other than that, expect to spend quite a bit- heads, intakes....