It will work fine depending on how the angle cut end of the tube is installed in the pipe.
There are 3 different ways it can be installed, and each way will give different results.
Some people say there is only one right way, but then get no vacuum doing it that way.
Going into the pipe at an approximate 45 degree angle and having the longest part of the end of the crosscut toward the engine will give the most vacuum.
Of course doing it this way could cause so much vacuum as to actually start sucking oil mist out of the engine and causing it to smoke.
Then there is RPM's to consider.
Do you want this to only have a good vacuum at idle, or higher R's?
My advice would be to make your hole for the tube and experiment with the angle and direction of the valve tube end until you get what you want.
Then weld it up.
You may even consider a ball valve in the rubber tubing on each side so you can limit the vacuum volume (especially if you put it in the way I described above, as that way creates the highest vacuum)
I can draw the different ways of installing it for you if you would like, and describe why each install gives different results.
In all three scenarios I would put it at least a few inches after the collector and before the glasspacks.
The highest speed of the exhaust gasses is acheived right after it necks down to the 2.5 pipe.
Of course there are other oppinions on all of this. :-)
