Ah. Well if they're the same price, go for it. I know on my Starion that the 2.5inch compared to the 3 inch on a stock turbo is that the 2.5 performs just as well as a 3, but with a bigger turbo it does make a difference. If you're planning on going bigger turbo, I'd go for the 3" then.
Now, on the car, do you have the crappy fabric "piping" for the IC?