Your call. I was stuck with Injen due to them being the only CARB legal one available and California is pretty strict about smog.
As for gains...you wont really get anything to be honest. The ECU will eventually remap the air/fuel ratio for best MPGs so even though at the beginning you'll notice it acting with a little more "pep"...that'll eventually go away after the remapping takes place.
Basically the intake/exhaust are simply sound/tone changers for these econo-boxes. If I didn't get mine from a friend who was selling his GE, I wouldn't have spent the money on either so-called "upgrade".
Now if you are going supercharger, then maybe a custom exhaust with larger piping will free up some power, but if you're doing supercharger you're also tuning...