The valve stem is undercut under the valve head. This helps both reduce weight and improves flow. The valve is then black nitrided, a surface conversion process that produces a hard, slippery, and wear-resistant coating
The exhaust valve is made of Inconel 751, an aerospace-developed alloy made out of nickel and chromium that is tough, wear-resistant, and highly temperature resistant. This is a pretty perfect material for an exhaust valve! 
The exhaust valve is oversize in diameter, 33mm vs the stock 32mm for better flow. To further aid flow out of the cylinder, the exhaust valves are given a tuliped contour on its back face and swirl polished.
12 comments
I’m surprised that your high-mileage S20 heads were rebuildable. No cracking in the spark plug thread area?
If it was cracked it wouldn’t be used.
Do you have any recommendation on A machinist that can duplicate this work ? Or if I can get this same work
We can do it for you. Go to the garage services link and get a quote.
199K is so much more like what these engines should have, beautiful.
Love the cam choice. I definitely feel like these motors are often undercammed given their displacement. Where are you looking for the powerband to be?
4-8k rpm
Cost to do your build on 2016 Forester XT? Do you build transmissions? Svt now how much
Surprised you went with a 10mm oil pump and not an 11.
Is it possible to do this rebuild or similar one with 205 ?
Yes
Im from Europe and I would like to rebuild 2.0 turbo 130kw (EJ205) Forester SG motor. Is it possible to have any consultations via email etc ?? It is not possible for me to ship my engine to USA and then back.