i have a 90 300zx. its an automatic car. i notice at times after driving it for a while that the boost only goes up to 5-6. i have a k&n fillter on it and it gets up to about 9 max. it seems to run stronger shortly after start up. any info....

Running low boost on a Z32 usually mean it is in saftey boost. This can be caused by either a ECU error code or detonation.

This link has a bit more info.

http://www.twinturbo.net/ttnetfaq/FAQpages/safetyboost.html