After doing some preliminary research I found out some piping sizes.

I tried using 3" intake tubes and filters and found that the car runs way rich and noticed almost no performance difference. If anything I think there might have been a loss in performance.

The ideal intake size should be around 2.38", so I'm going with 2.5" dual piping. If we were to go single 3" would be best. This size should be sufficient for 250+ hp, which I don't see too near in the future.

As far as the exhaust dual 2.5" also seems to be the best. Going higher then that will cause a loss in back pressure and a decrease in low end torque.

The next two restrictions are the throttle body and the cats, but I'm not sure what the stock size is for that. I'll look into it.