MBRP offers three grades. There is an aluminized steel, 409 stainless, and 304 stainless...which is also the order it goes in price lowest to highest. The performance one is the aluminized steel.
I have the 409 version on mine and I am happy with it. It has some here and there spots of light surface rust, but nothing that in any way is eating into the pipes.
I you have to worry about the rust at all, I would skip the aluminized version.
As for what comes with it, it depends what you order. I have the off-road system...meaning no provision for the cat. If you have smog testing to worry about, DO NOT buy this one.
The standard turbo back kit should have everything you need...however, if you want some good growl, you may as well order the muffler delete pipe while you are at it. It took me about 2 weeks with muffler before I decided it was coming off.
Another option is the cat test pipe. You can use this to pull the cat, then reinstall if the need comes up.
MBRP is some good stuff. I have been very happy with mine...it's been on for about 5 years now.