1. around 2000K to replace with new manifolds and labor ( friend pricing ) To gut them, around 300 would be fair given the amount of labor to pull the rear bank manifold. But I promise you that your mechanic will probably never touch your car again. LOL!!!
2. Definitely
3. Kind of
4. Depends on if you don't like the sound. And you already have a factory resonator. You can replace it with an aftermarket or remove it completely and have piping welded in its place.
5. You will surely be one step closer
