Basically the idea is to shut off half the dual volute turbine housing to make gasses accelerate really fast to the turbine wheel under low/part throttle conditions. As the boost builds an actuator opens the butterfly valve to allow almost a full open exhaust gas passage to both volutes. I say almost full as the shaft and butterfly are still in the path of the one volute but with it full open it is a minimal restriction.

Now, this is how I have mine setup

I have a pdi t4 manifold which is obviously divided. I have an ED t4/t4 1" spacer plate which my wastegate is welded to. This spacer was previously divided. I removed this spacer and undivided it with a combination of sawzall and cut off wheel/die grinder. Because of the wastegate tube interfering I had to run the quick spool flange with the actuator portion facing down not up. It was no problem to run it this way and have pleanty of room. Now, in clearencing the ED plate I didn't quite remove enought material so I get a little bit of interference as the plate tries to open all the way. Further, I placed a return spring on the opening lever of the flange to aid in returning the flange to the closed posotion in case of any interference. So far it's worked out wonder full for me this way. The actuator comes with a 4psi cracking pressure and a 10psi open pressure. I run a boost elbow with the adjustable allen screw in the air path to reduce the signal even further if I want for later cracking pressure. I have it pretty much backed all the way out for full air and may divert this regulating device over to wastegate regulation in the future, more on that later.

Driving impressions:

This turbo now spools better then the ball bearing t66 that was on the truck (s468 as the thread implies). Cruising egts at 70mph are about 100 degrees cooler and cruise boost is about 5 psi there, before it was about 2 psi. The turbine screams all the time now where as before the flange it was barely audible. Flooring the truck while not shifting manually now results in 60+ psi pretty quick. Before the valve the turbo would barely get to 60 psi. Now it pegs the gage in a hurry. I need to verify drive with this valve as my gut says it has increased and I may need to start using my wastegate. Without using the wastegate I previously had just under 60psi boost for 64 psi drive.

Keep in mind that I also bumped the timing when putting this flange on. I was fighting a timing issue which had me around 15 degrees at the time just prior to putting the flange on. I am now at 26* and the turbo still lights this much faster.

I honestly think these flanges have the ability to make large s472 and up charger more realistic for the street strip guy with some tuning. That too me is awseome being the idea of having small twin air with the same driveability all out of one turbo. Now, in a custom twin setup you could cover a much larger range of power.

Things that had to happen to fit the flange.

I had to make a spacer for my down pipe which consisted of welding two s400 v-band flanges together to move my down pipe 1" farther back. You will have clearence issues with the trans and frame if not atleast in my combination. Everything else required no modifications other then modifications I previously did to fit this turbo and gate (having to trim intercooler pipe on both ends to use current discharge elbow).

I believe there are going to be a few versions of this flange offered in the near future and if you were in the same boat I was in (wanting better spool out of a big single with the big single air) then imho you need to give one of these a shot!!! All that's required is a small small bit of fabbing and some ingenuity!