Originally Posted by gomer_110

It will lean it out a little bit (lean = less soot). The ECU will try and maintain the ideal fuel to air mix within limits. When I ordered my LTH and CBE I talked to Tony at F.I. and was told that until I go with a CAI I wouldn't need to worry about getting a tune.

The real draw back to any of the options you listed, especially test pipes and LTH's, is that the car is no longer street legal in terms of emissions. That's not to say that there aren't a lot of us running one of the options listed but technically we're all just hoping not to get caught.