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After a whole lot of googlin' I purchased a couple of these Electronic Wastegate Actuators. Doing it electronically I can guarantee exhaust restriction and VE across the RPM and MAP cells so the VE will be known and AFR's should stay under control. It'll also give me full boost control at all points in the map.

Google says they're either PWM or CAN controlled, the Hella versions support both so fingers crossed these do too otherwise I'll need to do some bruteforcing CAN bus addresses to command the vane position.

A little more googlin' shows these are dumb units, just direct motor control with a 0-5v feedback on actuator position. Removes the guesswork I guess!

Nifty.

I made a start on the microcontroller code last night to handle boost control. Please chime in if you can think of anything I should add now while its still in the proto stage

Here's where I'm at:
Maps and tables updatable via dragging and dropping the map file to the boost controller (Plugged in via USB it appears as a USB thumb drive). I think this is the easiest way to update the controller without any drivers or software.
8 analog inputs, 0-5v, high impedance (you can tap right into any existing sensor and it won't change the reading). I'm thinking Wastegate position feedback, TPS, MAP, Turbo outlet pressure, IAT, coolant temp. 2 spare.
Each input is 12bit and can be scaled through a config file (RAW to Deg C etc...)
2 PWM outputs - Hardware driven, 16bit precision. One for the Wastegate controller if it supports PWM. The other general purpose (fan speed, meth, etc)
4 General purpose logic level outputs - H-Bridge motor driver if the wastegate supports it, Pumps/fans/spark cut/2step/whatever
4 General purpose logic level inputs - Boost level, 2step, etc

I'm not sure how i'll go about editing tables. I'm thinking excel might be easy or somehow make TunerPro do it? I don't have any experience in coding for either.

Oh and I'll need RPM input too....

The silicone elbows, clamps, turbo beanie, exhaust wrap and o-rings arrived! Still no sign of my o2 bung drill bit, and still a week until I get my wastegate actuator. I'll wait to wrap it all until the bung is in and plumb the blow-off in when the actuator arrives.

I'll install the 2bar map sensor after lunch and see if its making any boost with the nozzle fully open. I'll also get a chance to see what the IAT's are doing at WOT.

The Wastegate controller code is good enough to manage the boost. It monitors manifold pressure and if under 80kpa it keeps the nozzle fully open for best effeciency off boost and once over 80kpa it'll begin controlling the nozzle position to maintain the demanded boost per RPM cell and keeping within the nozzle % limit per RPM cell. I think this will make tuning fairly simple as WOT at target boost will have a repeatable VE. Maybe.

Looking good! Im quite excited about this build

Thanks antus!

A Couple of questions - Will the brake booster be ok seeing a few PSI or will I need a stronger one-way valve? How about the charcol cannister or is it best to just blank the canister ports off?

I would put check valves on them both, or at least the brake booster and remove the canister. Not sure if its completely mandatory though.

Looks like the booster allready has a check valve weve fed over 20psi into a plastic commodore one with no issues

If you're boosting, how does it pull vacuum to operate the vacuum operated elements or do you rely on stored off boost vacuum to run them ??