I need to be educated on the L67. I was advised to check the bypass valve because sometimes I noticed the boost needle changes slightly under load...but it may just be the SC building up boost. I dunno...I have only 1 week of experience with this engine so far.

So what am I checking for on the bypass valve, where is it located, and what is the process?

I don't mean to show my intake pic again but you can see the bypass in this shot:



On the top of the supercharger in this pic you will see a vacume line distro system with one that comes out and curves to the right with a white stripe on it and leads to a black canister, that is the boost bypass valve.

make sure the vacume lines that run to it are tight and not cracked. Also start the car and rev it in park and watch the little arm that comes out of the bottom of it, it should move DOWN when you rev. This means it is closing the valve in the blower to stop the recirculation of the boost pressure to the top of the blower. It keeps all boost in the lower intake manifold. If this arm moves UP at all meaning opening you can have a fluctuation in boost under WOT.

So again, check the vacume line system and make sure it'* all sealed up. If you need to you can losten the bolt on the blower that the boost bypass bracket attaches with and the bolt on the outside bracket and slide the canister in a down and left direction closing the gap for the arm to close to a shorter distance. This is known as the boost bypass valve 'trick'. You will see boost faster as the arm will close before it normally would allowing full boost pressure at less throttle %age.

If you have more questions or need images/step by step, let me know.
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Disadvantages to this trick?

Disadvantage is fuel economy, as you hit boost faster at a lower throttle %age, it needs more fuel. I have yet to see any more problems with the trick than that. I tried it to see if perhaps my valve didn't close all the way causing a boost leak.. that wasn't the problem but now on the freeway in cruise control it will hit 7lbs of boost before it downshifts LOL.. gotta change that back

must be my computer.. it'* rex'd

Pcm can also pull timing and set a ses code if pulling hard and you let off the throttle.
Its an ok trick for the track but does have the ability to harm the engine :?

I don't understand, my boost needle moves upward every time I accelerate.
What is the problem I'm missing?

You're running the stock pulley. I don't think you'll see the problem until you get into higher boost levels.

Should be installing 3.4 pulley this weekend.