Toxic old bastard
One experience with the filter being the culprit.To test Eric's theory you need to remove the air filter and run without it and you need to do this before changing the governor.
How long is your filter? I ask because it looks like the same filter I have. The dirtier it is,the sooner it will collapse.
You asked in an earlier post if that turbo needed to be run at 30 PSI. It doesn't need to be,but it will produce alot of power at 28-30 psi in your application.
We had a Syclone on the chassis dyno. Wasn't putting up the #'s we expected.
While the engine was allowed to cool, we pulled the filter. A fairly large K&N cone, AIRC.
This resulted in a 15 RWHP increase.
In the current discussion, I'm wondering if the MAF being directly connected to the filter could be an issue.
I would suggest a back to back test, using a length of tube, that replicates the filter. This can help with straightening the air flow, prior to entering the MAF.
Back under my rock.