A tune without any supporting mods is worthless. You would atleast need a good proven CAI system designed for your car, a better flowing intake mani, and a nice branded exhaust system, cat delete, etc. Then maybe you can gain 15-18 whp on this engine.
The claim of a 10hp gain on a bone stock L13 is absurd. As Hassan said above, they will play with the ign timing, clean up your tp table, add fuel here and there for pops and bangs and make you feel a "gain" on hp.
If you really want to commit to this, add the above stated mods along with some meaty tires, a 6 puck clutch, and a lightweight flywheel, pair that to your short ratio gear and you would kick a lot of cars ass.