i bought a turbo kit with a 2 bar map sensor, and i see a bunch of people running a 3 bar map sensor.

could anybody clarify what the difference in them are?

 

depends what 3 bar you're talking about...the old brick style or the ZR1 map. the 2 bar is from a cobalt and is a direct replacement.

I'm personally running a gagetized 2.5 bar

 

mines a brand new on3 2bar map sensor

 

i wasnt aware china was copying map sensors too...

 

A two bar will read up to ~15psi of boost where a three bar will read ~29psi. You will need a custom os to take advantage of either. You will also need to change the connector for a 3 bar sensor, rather it be the gm brick or ZR1 sensor as there is not a pnp 3 bar sensor for the trucks that I know of.