I guess I am kind of confused, its all about what you are going for. You looking for seat covers or a nice set of racing seats? If you can find a part out car with leather seats I think that looks the best. You want to keep the grey interior but upgrade it? A common practice is painting a lot of the interior (like dash and door panels) black. You can always throw on a shift knob, shift boot, and steering wheel.

I am redoing my interior(very slowly, bottom of the list in priorities) but with a CF/black theme. Have a CF sticker on the inside of the gauge cluster. CF shift boot ($30 off ebay) and redid my sun visors to CF. Eventually I am going to paint the interior black... one day,as I said before, bottom of my priority list.

97 Talon ESi 14.943@91.35MPH N/A!
"If you need someone to provide an itemized build of materials and a flowchart to walk you through every build-related question you will need to answer at each step of the process, you shouldn't be playing with cars. "-Driggs