There are several posts on this. It's a 2.5L engine related issue. AVCS screens were pulled late 04. The oil screen line is left in. You can pull the screens. Pulling the AVCS won't help much. But, your AVCS screens should already be pulled. Pulling the turbo oil screen will prevent clogs and starvation...but don't ask a subaru dealership tech to do it. Because they'll tell you it still prevents a carbon deposit from making it's way to your turbo. Basically, i see it as a fail vs fail situation. Just make sure you change the oil religously and you shouldn't have to really worry about it. Unless you plan upgrading your turbo and will need the increased flow.