I have a Grimmspeed 3 port boost controller that is hooked up using only 2 ports. When I bought the car it had this boost controller so I didn't think too much of it but I have a changed many things since I got the car and was wondering if I should have this hooked up using all 3 ports?

In case it matters I am running Speed Density.

 

3 ports usually just use 2 ports as the other port is just a bleed port that you can plumb back to the airfilter pipe if you want. here is the grimmspeed install diagram that you could follow.
https://www.grimmspeed.com/content/i...ne_version.pdf

 

I looked at that diagram earlier but was wondering if there was a benefit to running the third port back to the intake or not?

 

There are multiple ways to run the 3 port as far as different setups go, for instance an external wastegate and pressurizing the upper and lower ports. With the current setup venting to atmosphere is very common and there is no benefit to connecting back into the intake pipe unless there is already a spot on the intake pipe open for a vacuum tube.

 

So if I switch to a catch can setup that's a good spot to run a line to where my existing valve cover to intake line is but there's really no benefit to running a breather filter on the valve cover just to hook up the third port of my EBCS?

 

the third port is meant to run to where the OEM line went: a small port on the bottom of the rubber intake hose.

if you plugged that hole (so you aren't sucking in un-metered air) and don't want to use it, you can just have the third port to vent air. the only risk is dirt/water/corrosion/etc getting in. for that reason, mine is plumbed to the intake. i'd at least toss a piece of vacuum line on it and face it down so stuff will stay out of the port. if it manages to get plugged, then better the hose than the port itself. in my opinion, anyway.

there is no need to run a line to the rubber line between the VC and air intake

 

im on SD and have 3 port.my intake pipe has no holes and i left my 3rd port open.3 years like that and no problem.