I want to run about 20 psi of boost on my 95 ls. I know I need a 3 bar map sensor but I'm not sure what kind or were to get it. I've seen these conversion box things that you wire in. Is that the only kind or do they make one that goes in the oem location that reads higher boost?

 

you can get a 3 bar from a jeep my friend did his that way and it works.

 

get a gm 3 bar map sensor.
wire it in, and just run a vacuum line to it.

Ziptie it up or something like that.