2 1/2 is to large. Go with the Stromung 2 1/4 setup. I have heard nothing but good things about it.
2.25 is the right size if you are just going to use bolt on mods. If you are planning to use nitrous I would go with the 2.5.BlackoutSpecV said:2 1/2 is to large. Go with the Stromung 2 1/4 setup. I have heard nothing but good things about it.