Its worth it, remember what it was like planting it when its absolutely freezing in the middle of winter? it will be similar to that in summer.

Also if you use boost alot in a short amount of time you will lose cooling efficiency alot quicker if your still using the standard top mount.

Im with trolley aswell on the turbo choice. td05-18 if you want less lag, td05-20 if you want top end power.

Seeing as you already have an exhaust you also need to budget for a Tune and fuel pump aswell which shouldn't cost you more than $1500 together.. as JDM_stylez suggests you should consider selling and purchasing an STi when you start adding everything up it is absolutely worth it!

Tougher internals, brembos, 6 speed, better turbo and intercooler. If you purchase an STi you will just need an exhaust and tune and your putting out better power than if you get the mods done to your WRX along with the rest of the package