My no.2 cyl was not firing properly at more than 1000rpm, causing unburned fuel and air to enter the exhaust manifold, igniting from the hot exhaust from the other cylinders. This was enough to spool the turbo and give positive boost in neutral. It was a bitch to figure out though, I only noticed it when I checked the timing for every cyl at different rpm, at over 1000 cyl 2 would firerandomly when 1,3 or 4 should fire (the strobe probably picked up interference when the cyl it was supposed to read didn't fire).

I changed the distributor cap and ignition wires and re-adjusted the ignition timing. Just took it for a test-drive and it runs great :)
It's a little gutless with the b19et cam but as soon as you floor it the boost gauge goes positive and the rear(s) start spinning :)