I'm more or less stock, but have had A LOT of work done at Turninconcepts.
They installed a new turbo when I blew mine last year and did an engine rebuild for me a couple months ago. Tony is the owner. I felt like I bugged them with me incessantly calling to check on the progress on the long involved job, but they stuck with me and they were awesome.
They work on performance subarus. I couldn't be happier with their work.
PM me if you have any specific questions about them or the work I had done... even though I haven't done any performance mods.
Their website is turninconcepts.com