COST: ~45 (tank and hoses)
TIME: 60-90 min
1 - Remove the POS old black tank (Remove 2 larger hoses, and 2 smaller hoses)
And purchase a WRX tank (mine was from an 02 and cost ~30).
2 - People have mounted their tanks in different locations, however the most logical for me was exactly where the ABS unit mounts (front left). If you look down at it, you should see a bold that you have to remove.
Remove it.
3 - Next comes the mounting bracket. I wanted to make it as simple as possible, so that people who don't have many tools (and cant weld) can do it (and plus I like to live by KISS).
Start with a 90 degree metal bar (not sure the exact name for this, I had this bit laying around).
This metal bar is going to attach to the ABS and straight up to the coolant tank.
We guessed the length, and just cut it down until it was the optimal length, which turned out to be 7 1/8th Inches long (7in will work fine). Next part is to drill a hole for the ABS bolt. Keep in mind that when attaching this bar, the 90 degree bend will be towards the back of the engine (with the lower inlet on the reservoir tank will be on the right side at the front).
The second hole will be drilled at 5 3/4th inches from the bottom. To get an accurate location simply place the tank on the metal strip and mark it. When placing the tank on the bar, make sure to tilt it just slightly so that it sits in the 90 degree corner.
Next comes the second hole. Attach the tank to the bar (I used 8mm bolts all around I think). Then, you can drill another hole for extra security, that runs through the tank and through the metal bar. (see picture above)
Before you can bolt in the other bolt, you may need to grid it down a bit so the bolt will be flush (I just used an angle grinder, and a dremel)
Like I said, when this is done, simply use 2 8mm bolts to secure it. Simply place the tank in the engine bay, and wiggle it onto the bolt sticking out of the ABS and tighten it up. It should look something like this.
Next comes the hoses. You should have pulled 2 large hoses of (1/2 inch maybe) and 2 smaller ones (1/4 inch maybe). You will need to go out to advanced auto or somewhere to buy some more hoses (just take the samples you pulled off with you, they will hook you up). I picked up 6 ft of the bigger hose, and 3 feet of the smaller one for about 12 bucks. (Your lengths might different, I had some of the 6 ft left over, and wanted to replace more of the smaller one, so I ran out of that)
To make this easy I tried to color code everything
Image 1 is the path of all the hoses in stock location.
The next 2 images are how they will be routed when the tank is in the new location.
Some notes.
The red hose can be simply ran from the plastic tank across the front, to the coolant tank. I decided to make use of where the blue hose use to go and connect it to the metal pipe that runs across the manifold (as seen in the picture).
The best way to do the purple hose is to thread a metal wire through the pipe and use that (and a screwdriver so it doesn't get caught on screws) to pull it under the intake manifold and between that and the alternator and what not.
The green hose simply runs from the turbo, between the black intake and the intake manifold and just over top to the tank.
And obviously the blue one simply goes from the radiator to the tank at the front.
Fill it up, I didn't even bother burping it, it should be fine. Keep topping it off while it idles, until its at the right level.
Note: Use the cap from the legacy tank, not the one from the wrx tank, they have different pressure ratings.
That it, you should be all good to go.
Good luck and post back with any questions.
Much love
Ben
Special thanks to Matt and Dad
i need something soon.. This Thead would be so much better if it had a link to a page that you can find the tanks.. As far as the intake pice for now i have duck tape 
but i need soon. Im plaining on picking up a TD04 soon If its worth it.. lol if i pick up a silcone intake for the stock vf11 will it fit the td04? Im goin to try to find a place that constantly sells these things so we can have a link.. if someone has been here before.. wich im sure most have.. Help us fellow subie fam..