Ample frustration at not being able to make the bloody valve move.
Take one flat punch
and one big hammer.
Simmer gently for about 1.5 hours of head scratching then take the punch (I do suggest you use something more fitting to distribute the load) and with a generous helping of hammer take to the valve face.
You'll end up snapping the spot weld in the center of the valve holding it to the brace running through the center of the exhaust port.... and now you have a functioning antilag actuator... what you'll do with it considering you dont have a trigger, I dont know.