I have the APS TT kit on my 04 350Z. The boost is set at 9psi; however, my boost started reading at around 6.5 - 7psi all of a sudden. I checked my boost gauge and its hooked up fine. Also, the car feels noticably slower so I do not think it is a bad gauge. Anyone got any ideas? Bad boost controller? Clogged Cats?

 

very first thing you should check for is a boost leak somewhere in the IC piping.

 

it's getting hotter outside too