presumably It's the engine management. If I could get the knock out of the picture I think another 4-6psi will get him 250ish wheel.
I'm basically going to tell him to get the stock MAF on there so the timing is in the window it should be. Also the intake side could perhaps use some more spring pre-load.

Well anywho. Zenith Diaphrams? huh? lol electronics is fun!

The ol solstice will be spending the next few days in the dyno shop. I still haven't made an intake. Im using a piece of 3" neoprene brake ducting hose and a C6 airfilter.
I want to try
1)running it as is
2)Running it with nothing on front of the turbo.
This will illustrate what the proper size should be for the Air intake.

then I will build the intake without moving the car (you can change HP just by strapping it down different.) to see what we end up with.
The I'll run it with just a pipe extension with the downpipe & O2 to see if the Exhaust needs to be bigger.
Then we'll see (pending pressure drop) what garrett intercooler core will fit best and fabricate a new intercooler for it.