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If you can use a drum sander on an electric drill you will do fine with the transistion casting. See old posts to review objectives.
The $129 TurboXS unit, and the other enhanced bleed valves with ball and spring mechanisms all work pretty much the same. The ball and spring keeps pressure from opening the wastegate until a certain pressure threshold is reached. This prevents intermediate pressures from causing the wastegate to start opening early, which delays the achievement of full boost. Ordinary bleed valves have this problem, so does the stock boost system... but I will not go there.
There are lots of people who look down there noses at bleed valves. That is their bad attitude.
All bleed valves, including the stock system, increase boost pressure by only letting the wastegate actuator see part of the pressure. This requires a restriction and a leak or bleed orifice downstream. A basic bleed valve will have a restriction orifice and a variable downstream leak or bleed to atmoshpere. But a fixed orifice bleed and variable upstream orifice can work as well.
With a ball and spring enhanced bleed valve, the ball and spring creates the non-linerar flow behaviour that is sought. It also provides the restriction as well. The spring tension is adjusted with a screw of some type. Downstream there is a fixed orifice.
The HP TurboXS unit also has a variable bleed orifice that can be adjusted to get some changes in the characteristic. But I was not able to use that to remove my cold weather pressure overshoots with a manfold pressure tap. This valve also has a restriction upstream of the ball and spring. This is a carry over from their basic bleeder valve. I wanted the wastegate to be able to open faster to get rid of my overshoot, so I drilled that orifice to get more flow once things started to flow.
I don't see why the $35.00US delivered unit would be any better or any worse than the alternatives. There certainly is no evidence that you will get a better result spending $100 more.
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