I was out running around with my cobalt trying to figure out my Max boost, which turns out to be 11.2 psi. I've been reading stock M62s should be making 12 psi stock. The only thing done to my car is a Magna flow exhaust system. My question is do any of you think I have a problem? Or maybe know where I'm losing that pound of boost? Or could it just be that my cobalt was the runt of the litter?
Thank-you!

 

According to what you said you are only .8psi off of what you think you should be making. Definitely not reason for concern. How are you even reading .2 on your boost gauge lol? Boost levels are dependent on many variables. Even though your psi difference could just be chalked up to sensor error or something else as it is minuscule you could have had a slight pressure drop from freeing up restriction in the exhaust. Less psi with the same airflow is a good thing.

 

Oh alright that makes sense, sorry I'm new at this lol. I didn't read it on my boost gauge though I have a complete computer diagnostic system that gives me an exact reading lol.

 

Many reasons why boost won't be exactly at 12psi. Like jdbaugh1 said, you can have less boost if you have better airflow through the engine from the exhaust. Boost can also be higher and lower because of temperature, humidity, and barometric pressure. Higher altitudes will have lower boost numbers then lower altitudes. The more dry the air the lower the boost numbers will be.

 

Your exhaust could very well be the reason for the lower boost pressure - the stock muffler alone was proved to rob 5-8 whp

 

He said, she said... that's old data

Stock catback does not hurt flow. (So far proven to near 300whp)


Another good read is when Infraredline unbolted his cat-back to see a negligible 1whp gain.
https://www.cobaltss.net/forums/dyno...esults-319528/

 

I wouldn't be too concerned about it if you had more boost and then your getting little out of it i would be looking into it.