How accurate is the old AP at reading boost? Actually I guess I should rephrase that. How accurate is the cars computer at reading boost levels and passing them on for us to see on the AP. Reason asking is because things I have seen are not making sense to me. I have not touched a thing on my car in 3 weeks yet I am showing a 2psi difference between this morning and about 2 weeks ago at night. I really can not see where the weather can make that large of a swing. Difference between the 2 places that I took readings is only about 50ft elev. diff. Air temp is maybe 5 degrees cooler today, humidity is a good bit lower, 48% today compared to about 65% that night. Once I get some breakfast in me I am going to go out and check for loose vac lines or maybe the wastegate arm rubbing the heat shield.