So on some of the build threads, guys with post '04 donor cars are trying to figure out what to do about the in-tank fuel filter. On WRX's from 02-04 Subaru used an under-hood fuel filter that looks like this.

On the STI and WRX's after 05, they use a 'permanant' in-tank fuel filter. Initially there wasn't even an individual part number for the in-tank filter by itself, subaru said it didn't ever need to be replaced and only was sold with the full in-tank assembly. Now they just try to charge you for the whole housing and canister but you can buy the canister/filter media by itself.

I did the conversion at 90k. When I got the original filter out of my car and cut it open, I found it was made out of basically rolled up cardboard and was filled almost completely with sediment. Like I said though, the STI's and 06-07 wrx's have a nicer filter but the PITA alone to need to pull the pump out of the tank to replace the filter is enough to consider doing the conversion.

It's easy. Just remove the filter from the in-tank assembly and replace the span between the pump and the fuel tank plate nipple with a corresponding length of Fuel-grade 3/8'' line (I think it's 3/8'' at least). Next you just take the old canister type filter and pop it in-line on the top fuel hose going to the engine.

Here's what your in-tank assembly will then look like after removing the in-tank filter:

Here's how you can install the filter keeping that little magnet damper thingy, I removed mine since they don't really do anything. It goes on the top line connecting to the engine.

Doing this will save you a few bucks and make it a lot easier to change your fuel filter more regularly.