New & Question.

Hey, new X-Terra owner (08 S Model), and new to this site. Just wanted to drop a line to everyone, and I also have one question (that I'm sure you have heard countless times before). What performance-type modifications can be done to my truck without really voiding the factory warranty? I'm not looking for any miracles here, just something to give a little more pep in the step. I had a Mustang GT before this, and quite frankly, I like some power in those rear wheels. Thanks in advance, and I have to admit, this site seems pretty cool so far. )