The GSX air intake is under the seat, it has two intake "horns" (my word) that point down and rearwards. If you remove them and the foam that sits under the filter you get a power boost. Not a huge top end amount but significant mid range.
https://www.youtube.com/watch?v=4ZfJu9VDiWM
The same guy that produced the above video is reflashing the ECU which gains more power. I'm not particularly interested in the power increase but one thing he mentioned was how Suzuki has softened the initial throttle response to prevent a snatchy throttle - he takes that out for one of the rider modes. I'd consider paying for that (if he wasn't in the US).
Here's the reflash video:
https://www.youtube.com/watch?v=Pa7bh1xZxJc