Originally Posted by kilfarsnar
The splitter is a horizontal plane that attaches under the scoop and behind the vertical vanes at the mouth. IIRC the WRX doesn't really have a splitter. It's not needed with the smaller TMIC.
The splitter's purpose is to direct airflow evenly over the intercooler. Without it the air would pile up at the back of the scoop and not flow over the entire intercooler. Just FYI, your hood scoop is the same as the STI for your year, so you don't need to replace it. The splitter and the boot (that seals around the intercooler when the hood is down) can be had at subarugenuineparts.com.
Okay I gotcha, so the splitter is needed then? How do you modify the Wrx one to be like an sti like the one person was saying??