Does anyone know if a stock 2018+ STI type RA block would be legal in a 2004 STI running in STU class? Looking to refresh the stock motor and hoping just to mainly gain reliability.

I am afraid you cannot. A new oem shortblock for a 2004 sti would be the easiest way.

I autocross my 2011 STI sedan in STU, here's the details:

1. Engine
2. Exhaust
3. Suspension
4. Alignment
5. Tires

1. Stock STI motor, stock TMIC, COBB SF intake, Pro Tune, Killer B Super-G EJ pan with pickup, Koyorad radiator, Crawford AOS
2. Invidia Q300 turbo back, Perrin up pipe, stock exhaust headers
3. Stock struts, stock ride height, Perrin 25mm front anti-sway, Perrin 22mm rear anti-sway, offset top hats, some STI group N stuff
4. -2.3 camber up front, -1.5 rear camber, 0 toe front and back
5. 275mm Falken Azenis RT660

And some extra things that doesn't really have a category up top. I've got a Kartboy short-throw, and a JDM STI Group N power steering cooler. Also, I just got a new clutch (Exedy Stage 1, was on the OEM clutch), currently breaking it in. And I've got some Whiteline springs that will be going in soon.

Here's some pics on course!








And the engine, should look pretty familiar:

Your discussion about market research tools was very informative. Check out the group purchase options for buy junglescout group to increase efficiency.