I'v searched and read about this but I'm having trouble understanding. If the cobb AP reads boost in PSI and the AEM gauge reads in PSI why do I get such different readings. At wot I'll see 18-20psi on the AEM gauge but the AP says I'm boosting at 26psi. I'm on OTS 93 octane LWG map for now. Cars a 2015 gsr with test pipe and catback

 

The AP reads data directly from the ECU, the boost gauge compares manifold pressures to barometric pressures. For me, my boost gauge generally reads 3-4 PSI than I'm tuned to.


Someone else can probably explain it in more detail, this is just my understanding of how it works lol.

 

So the Ap is more accurate or the boost gauage?

 

Now I'm not an expert on these items, but from my experiences and from the information I've gathered...
The AP is a great tool for tuning and for a variety of information but that's because t reads it from the information the ECU gets.
The Boost and O2 wideband gauges measure the information directly from the vacuum lines and downpipe therefore making them more accurate.

 

Interesting. Hopefully when I get protune I will know more. Because if the AP is correct then I'm over boosting and if the boost gauge is right then that's probably what it should be boosting too on the stage 2 lwg map