Man, I've done a lot of work on this, crunched the research. WISECO has an off the shelf piston that if I called them and ordered them without valve reliefs, would work great. Yea, I've got lots of numbers. Turbone I read that thread, got some thoughts will post later. I can do some pics now. Oh, I'm fairly certain I can fit an EJ20 factory piston successfully. And it wouldn't be such a bad fit. I can fly cut any valve reliefs. Depends on id there is enough dome thickness. Aftermarket turbo usually a quarter inch plus thick dome.
Here's the specs on that Wiseco. Oh, scroll down and read the last sentence first.
Part Number: K588M925
Notes: Pro Tru Pistons; Sport Compact Series; Set of 4 Pistons; Recommended RingSet: 9250TX; Rings & Pins Included
Dome Volume: -9
Comp Ratio: 8.35:1
Comp Height: 32.66
Gram Weight: 380
Product Category: Pistons
Fits JDM WRXSTI EJ20 2.0L; 16Valve; DOHC; From 10/98 Production Date
Wiseco Pistons - Pro Tru Sport Compact Series: World
renowned for our work building race winning pistons, Wiseco utilizes
experience from a diverse background of the most sophisticated sport
Sport Compact Pro Tru line creates the best value in forged pistons
today. These American made pistons are forged and machined by skilled
Ohio craftsmen with state-of-the-art forging presses and CNC machines.
By using dedicated forgings specific to the final piston shape, Pro Tru
pistons are stronger and lighter than industry standards.
Tru sets include plasma moly 1/16, 1/16, 3/16 pre-gapped ring packages
which provide excellent seal, friction reduction, and long life. Pro Tru
pistons also come in a variety of volumes that allow the engine builder
to choose the exact compression ratio required for their engine.
Edited by Quidam, 02 October 2013 - 12:03 PM.