After switching from a Turbo XS manual boost controller to a Grimspeed 3-port electronic boost controller, I've noticed that my needle on the boost is not smooth like it was on the MBC.

Any help would be appreciated.

 

Is your boost gauge with electronic sender?

 

On the Grimspeed, I have only 2 port of the wires on, bottom right is open.

 

Is your ebc tied to a tune on your ecu?

 

Right but how your boost gauge connected? Does it have electronic sender( small black box) or line goes streight to the gauge?

 

You need a filter or a restrictor pill at the sender.
Look at expensive kits like HKS and you'll see the in-line filter(s).