You must be talking about the catback. The axel back IS a direct bolt on. I put it on my siters Ex in about 10 minutes. No problems at all.Its not a direct bolt on. I have an 06 si, I tried to put it on my girls 07 Ex and its off slightly, but it was modded to fit. It makes the car sound a whole lot better. Deff worth it if you can get the si muffler cheap or free.