Mechanical or Electric boost gauge?
 

I want to replace the boost gauge in my 05 SS with an aftermarket one, is the factory gauge mechanical or digital/electric? If I buy the same kind of gauge as the factory one I should be able to just swap them out, right? Also what size is the factory gauge?

I don't know for sure what drives the gauge. I'd assume it would most likely be electric though since the pcm already has a map sensor input to be able to read manifold pressure.

As far as just replacing 1 gauge though, that's not going to be easy. The cluster is all 1 piece, so it's not as simple as popping 1 gauge out and popping an aftermarket one in. Maybe you could cut just the one out, but I know on some of the older clusters, one circuit board ran across the back of everything (in order to provide lamp sockets for illumination and the various warning lights), so that would make it almost impossible to cut a section from.

I know that general timeframe of GM gauge clusters had stepper motor issues, perhaps that's what the problem is? I remember seeing some threads a long time ago about sending the cluster out to have the stepper motors replaced/upgraded. Maybe that's an alternative to buying a total different gauge and trying to make it work? I believe the screen name of the guy doing them was like bbengineer or something along those lines.

Yea the board is right where youd have to cut.. I was gonna do this myself but its impossible..

It is most likely the stepper motors and theres three options for fixing this,

You can but a cluster with the new (improved) stepper motors in it,

You can send your cluster off to have the new ones put in,

Or you can just buy the upgraded motors and do it yourself.. Its easy but its a real pain to line up the needles and get them exactly as they were before..