small edits made. More details added in a later post.
This is on a 97 ej22e. This seems doable for any second gen 22e and it may work on the 2.5's as well but I don't have one to test so I can't say 100%
Here's my recipe. There will be a couple set backs for those without a welder or tube bender. Most exhaust shops or metal fab shops know how to weld and will bend some tube for a small fee. I'm still working on details and adding stuff as I go with this setup but my car is running 100% reliable right now and any future improvements will just be fuel economy, idle speed, and boost pressure.
22t turbo bracket. Your 22e is already tapped to mount this to your car. Just bolts right in.
Turbo. I'm using a VF10/vf11 (same turbo. First Gen Legacy turbo). I'm sure a td04 would be about the same but I had some reasoning for going with this tiny little turbo. 1. Anyone that does any sort of tuning with 1st gen legacies immediately looks into turbo upgrades so they are cheap(less then $100 most times around here). 2. This turbo has a 5psi wastage which just makes all of this easier since I'm shooting for reliable boost to really just give this car more pep. 3. I know this turbo is unpowered but that just makes things feel a little safer to me. This turbo is small and if it does over boost then its going to be a small scale instead of massive boost spikes. No need to get greedy when I just want a safe DD.
Up and Down Pipes. This is part of where the welding and tube bending come in to play on this build. Get the ej22t ones if you like. Thats what I used and they worked great. Your going to chop them up anyway so whatever is cheapest is what your looking for. The up pipe will have to be custom to get it to fit. In all honesty I think that one small part took as long as the rest of this build to get it just right. The down pipe will bolt right in to the rear of the turbo and the factory mounting location off the transmission will also fit it like its supposed to be there.
Exhaust. Right now I'm using the factory 22t exhaust. Its quieter then my old exhaust was even though I'm running cattless now. If you want louder go to 3 inch instead of 2.5. I Gutted both cats and bolted it all up with a 4 inch can in the rear. It has a nice tone to it but doesn't drone at all and is quiet enough to not draw too much attention. I had to add 3 inches of pipe to the mid pipe to make it mount up in our cars. Aside from that everything went right in and the hangers matched up.
Headers. This part is tricky. I will attach some photos below with the single port turbo headers that I made. They are far from perfect but they do the job and they don't leak. Plus now the a UEL so you get a nice rumble from them. You will need some 1.75 tubing to make these and two more flanges that mount to the head themselves. I went to the junkyard and just pulled two flanges from a scrap car but you can use whatever flanges you want as long as they meet up right.
IACV from a eg22t. The parts numbers don't match up but it fits and works. I have one in my car right now and it is actually working better then the stock one I had before it(mine needed a good cleaning I think). Instead of going straight up like the 22t one does yours comes straight out and it will hit the turbo once everything is bolted in place. Basically ours looks just like the 25d one.
Hoses. You will need 3/4 1/2 and 1/4 in various lengths. You will need to tap into your heater lines running from the intake manifold to the heater core. Just tee off of them and run those water lines to your turbo. Direction of flow doesn't really matter here. Water in from one side, out from the other. You will also have to move your head breather tubes. Depending on the intercooler you end up with some will have the breather hard line along the bottom of the cooler. You need to run both head breathers to that and then tap back into the cold side of the turbo. On the stock setup they run to the black box right above your throttle body. You also need to tee off your brake booster line for your boost gauge and your blow off valve so it seems vacuum and boost. The brake boost line is 1/2 so I used a brass 1/2 x 1/2 x 1/4 tee for this. You will also need one more 1/4 x 1/4 x 1/4 tee for the boost line and BOV line to tie together.
Oil Filter Sandwich Plate. This will be your oil feed line for the turbo. I bought the Glow Shift Oil Adapter Plate with m20 p1.5 threads. It has three 1/8 npt ports and two plugs in the kit. It doesn't leak and feeds the turbo just fine. $25 bucks on ebay give or take.
10an Oil Drain Return Plug. This is a part I had a hard time finding for a while but ended up with two of them in different styles when I was done with the build. If you have a welder and are confident to weld a oil pan the I would buy the 10an male threads weld on nut. It ran about $10 on ebay and its what I ended up using in my car. If you don't have a weld the other option is 10an drain nut that has a small O-ring built into it that should make it so you don't have to weld it to the pan. This wouldn't be my first option but it sounds like a lot of people have had success with both. You have to drill either your head or oil pan either way so pick whatever your comfortable with and drill a hole. The non weld one was somewhere about $20 bucks
10an Double Braided Stainless Steel Hose. I bought 3 feet because that was the minimum order length to get free shipping. I might have used a foot and a half of it total. It would be much less if you tapped your head instead of your oil pan. This runs from your turbo oil drain to wherever you tapped your hole. I used a hose clamp on the turbo side and a fitting(see below) on the drain side. $10 give or take
Straight -10an Swivel Oil Line Hose Fitting. Search that on ebay. You'll find it. I connects to the 10an hose and goes to your drain. It gives you a nice tight fitting and looks much cleaner then a hose clamp. Less the $10
Magnetic Oil Drain Plug. Not really part of the build per say but its a smart thing to have installed next time your doing an oil change. Especially since you just drilled your oil pan and most likely didn't get every single tiny piece of metal shaving out of the inside. I like the piece of mind.
Turbo Braided Oil Inlet Feed Line. (again, just search that on ebay). One side of the line I ordered is a male 1/8 npt fitting for the oil sandwich plate and the other side is threaded female m10x1.5. Thats the size you will need for the VF11. (I think the td04 is m10x1.25 but I don't want to spread the wrong info around so do your research) Line needs to be about 36" long. It could be a little shorter but I would rather have some extra length to work with. This kit came with a bunch of other fittings but I didn't use them. Less then $20 on ebay
Oil feed Banjo Bolt. Tricky little part to find. 10mx1.5 to 4an Banjo Fitting Kit. Comes with your brass washers, banjo bolt, and banjo fitting for the turbo. This will fit the vf11 and works perfect. Check the thread size for td04 to be on the safe side. Under $10 on ebay.
Silicone Elbow. 2 inch to 3 inch. Needs to be 90* and try to find a nice tight bend. This is a spot where the TD04 will be much different. That turbo doesn't have the 90* fitting on the end that the VF11 does so you will have to route your intake a little different if you go with that turbo. About $20 on ebay.
Intake tubing. 3 inch. Needs 3 to 4 lines going into it depending on how you route everything. Crank case breather needs to go in here, head breather tubes also, and IAVC at a minimum. Depending on what you do for a BOV you can vent to atmosphere or vent into the cold side like the stock setup does. More on that in the BOV section.
BOV. Edit: Read my newer posts for more info
. You still can vent to atmosphere if you can't live without the BOV noise or you can set it up in a stock location back into the cold side. Some will probably want to yell at me about venting to atmosphere this but due to the fact that this car was never supposed to see boost anyway I really don't think that venting to atmosphere is going to hurt anything. The stock subaru by pass valves vent to atmosphere just fine by just not connecting them to the intake so don't go waste money on a noise maker if that is what you are looking for. I will post some videos when I get a chance sometime soon so you can hear how it sounds inside and outside of the car with just the factory valve. The other plus side is most people are trying to upgrade to an expensive noise maker so these can be had super cheap.
Intercooler. Edit: Read my newer posts for more info
Legacy GT 2005-2008 I believe. Forester XT 2004-2008. WRX 2006-2007. Stick to those for the least amount of headache. Yes the 02-05 wrx intercoolers will work but your going to be doing a lot more cutting and bashing or your firewall to get them in right. More on this to come, I still don't have mine installed so I'm just running the 93 legacy charge pipe straight from the turbo. The high that is has been here since this setup is 20* so the air is more then cold enough to be able to get away with this. Too much warmer and I would be worried about putting too hot of air into my throttle body.
Gauges. Boost, A/F, Oil Pressure, Coolent Temp. More to come on this. The only one I currently have in is the boost gauge. I haven't had my car above 4k since it has seen boost and it will stay low on the RPM's until I can at least monitor Air to Fuel ratios.
Notched crossmember. Buy a turbo on and swap it or notch yours and reinforce it. Either way works. One is much prettier then the other but they both seem to work. Google images will give you an idea on how most people do it. This photo is just for example. I did not have to pull the motor in order to notch the crossmember.
Things still to come. This will come slowly over then next few months as I get more spending money for the car. Wideband. Manual Boost Controller, FMU 12:1(I'm going to be running the 12:1 with the manual boost controller tied in inline so I can limit the amount of boost the FMU sees in order to dial it in. EDIT: I may be going with an Emanage Blue now since one just popped up locally for a good price), Oil Pressure Gauge, Coolant Temp Gauge, 3 Pod Gauge cluster(still working on finding a good place to install these so they aren't out in the open but still easy to see. I might make a custom cluster to go in the extra din hole around the radio. The 3 pod single din thing you see on ebay doesn't fit. Not even close. Learn from my mistake and don't waste your money on it).
Ask away with any questions you have and I will gladly do my best to try and help as much as I can.
I will also try and get that video made this weeks sometime so you can hear the BOV, exhaust, engine idle, and see it all in the car.