i have a greddy type s bov an diw as wondering if i took my stock bypass valve off (7mgte 1987) will the greddy open and work correctly also hte little vacuum line on the stock bov can i just plug it or do i need to run it to my new bov what does it do
It shoud open yes, but the Greddy Type S is the most piece of shit BOV you can use. The MK3 does not like it. Idle problems, stalling issues, extreme rich conditions, and faulty BOV's are only a few of the problems you can possibly run into. I went through 3 of them myself before going with something better.
If you do keep it and decide to use it, you will need to use the vaccuum port on the new BOV. This is what cause it to open.
Obviously blinded by his fury regarding Greddy Type S units , Trent failed to mention that - like most aftermarket BOV's - the Greddy has an adjustable opening pressure that can be tailored to your boost level, whether it is stock or otherwise. Be careful venting any BOV to the atomsphere on an AFM monitored car like the MKIII, for you may have stalling issues when lifting off the throttle suddenly out of gear - like shifting.