i own a 98 gs 400 it is my 4th one and i am keeping this one so i want to make it faster i have a greddy evo 2 cat back, srt intake and i need more i hear you guys talk about some piggy back units so if any one can help me out and tell me what els i can do to it. i am looking for a supercharger so if any one has one for sale give me a price.