Nope..the trans is ticking the second the car comes off the assembley line. If you don't plan on upgrading the trans, don't bother modding. Skip the k and n either way, make your own intake. Headers are mega pricey for the gxp. And all you need is one tune. Iirc gxps have pcm's just like the gtp. One computer controls both engine and trans. Find a competent tuner and get a solid tune after all your modss are installed.