I'm wanting to build a 2.35l stroker and put a turbo on it and put in my 1998 legacy. What all would I need to stroke it and what's the best size turbo for great low RPM power? Help.

If you want low end power look into a supercharger. Turbos don't do so well at low RPM because it takes time for them to spin up and start making boost. A smaller turbo is "better" for low end, but won't beat the response of a supercharger.

I didn't know they made superchargers for a Subaru EJ22. I'm still wondering if making the 93 engine a stroker will help.

If you can mount the cat BEFORE the turbo, like a really small and short high-flow, you won't have the back-pressure in the turbo housing, but turbo needs to be as close to the cat as possible as the hotter gases offer more velocity.

 

Other option is a 3" down pipe with 3" to 4" high-flow cat, as that'll lower the back-pressure as well, allowing the turbine to spin easier. Straight-pipe (no cat) on a smaller exhaust housing turbo, offers basically instantaneous boost. When I was still running a GT2554 in my Saab, and had a straight pipe briefly, it went from complete vacuum to 15 psi in under a second. It's hit around 12 psi instantly. That was with a hollowed cat carcass. A 2.5" mandrel downpipe probably would have increased velocity, improving response further.

 

If you have the money, modern ball-bearing turbos are the way to go. Garrett has their GTX line of ball-bearing turbos that are very responsive and offer improved blade designs, which improve spool-up, but you still need a high-flowing down pipe and muffler to compliment them. Steeper final gearing (4.10's, 4.44's, etc.) gets you moving quicker, and higher stall converters on auto trans can get you moving quicker as well.

 

Biggest mistake people make with turbos is overly large exhaust housings and turbines wheels, with larger compressor wheels. They'll see little boost until almost 3500 rpms, and if they ever show a dyno graph, you'll see the engine barely makes NA power from off-idle until 3500 rpm, then all of a sudden it jumps to what the turbo can do, but in some cases it's intentional as they are in FWD with weak trans, shafts, etc. and the set up tolerates the power later in the revs better. 

Not aware that a 98 Legacy was available with a turbo. If that is true, then trying to install a turbo, when not wired for it, creates a big problem. I would suggest building a Franken motor for more power.

Think he's planning on running an aftermarket ECM. Running a turbo creates no issues when a safe tune is applied and you aren't exceeding what the engine can handle.

 

 

As mentioned further up, a supercharger is an option too. Retro fit a supercharger from something that came with one, and they can be had for several hundred dollars in take-off condition.