Well as i recall the 07's come with the LSJ exhaust manifold from the factory. So really the only thing you'd need is a new larger diameter downpipe/catalytic converter. I just replaced my 06's manifold and downpipe with some used LSJ parts. The LSJ downpipe is fing huge compared the factory 2.2 pipe which drops back pressure to nothing. However replacing the factory cast iron manifold with a tubular header will take some weight off the car.0kay so i am putting a new exhaust system in my car as well as new header i have an o7 ls and wanted to know witch header u exactly use in this situation
A catback system is just that, from the catalytic converter back to the rear bumper. It doesn't include replacing the catalyst, that would require a downpipe and possible manifold swap depending on your setup.You also have to decide if you want a 4-1 or a 4-2-1 header. Different airflows and different results at different RPMs. Here is something I wrote up a while ago.
There are a large number of companies that sell exaust for the 2.4, 2.2, and 2.0L trim levels. Borla, Flowmaster, and Pacesetter are just several examples. Now, you can buy a catback system that usually includes piping, a muffler, and a cat.