I tuned my FG, tuner used the X4. picked up about 15kWs... from 186 - 201rwkws. Is yours an auto? because if it is spend the little extra coin to get the gearbox tuned - it changes the entire driveability of the car. the shifts are heaps quicker, like waaaay quicker, and the converter locks up a lot better. Also you get little extras which are cool like a raised rev limiter (doesn't need it at all lol) and removed speed limiter. It's definitely worth it if you've already done the cai/exhaust/headers etc.
Also consider doing reduction drive pulleys first, that seemed to make a big seat of the pants difference.
