I got a little bit drunk
Pulled a cam cover off, can't see any shims in there so it may not be a NEO head, which would mean I have been ripped off
Didnt see anything obviously wrong, and then spotted the stainless exhaust manifold was snapped almost in half. That could account for the funny noise, lack of power and boost, but not the low compression. But I don't have a lot of faith in my compression guage so yeah...
So the plan is to put it back together with a factory manifold and see how it goes. If its still f**ked, I'll take it somewhere for a compression test and leakdown test to work out whats wrong. But hopefully it wont come to that.
Need a new exh gasket and some other misc stuff though, but will hopefully be going back together next weekend. Oh, does anyway know where I can get the right sized copper washers for the banjo bolts? Super cheap/rapeco etc only have imperial ones.
Gonna be spitting chips if this head isn't a NEO one but.