Whoa there Big Wallop,
The vented stacks on your house are there to draw air into the system when
you put water down the pipes. It is not there to let gasses out. If air was
not admitted then as a column of water dropped down the pipe it would cause
a vacuum to be formed behind it and it could and almost certainly would suck
dry all of your water traps on that system. Not a good idea in having no
water trap in your toilet, waste to bath etc.