5k will get you pistons installed only, which will allow you to run more boost.. but you can kiss your block goodbye at some stage, as this is the real weak point when running big boost in a 2.5 litre.

My recommendation is enjoy it as it is, or go for a JDM EJ207 long motor if you want to be unique and not spend $15k doing it properly.. plus you can sell the stock motor and recoup some cash.