It's nice and warm (50f lol) so I went out and checked to see how the boost pattern was doing, i'm finding it makes 10psi to 4500, comes down to 8psi like it should, goes to ~11psi then after 6000 or so it comes down to ~8-9psi to redline, I think my last one acted like this too... only mods are apexi intakes/downpipe/greddy catback, stock cat in place

sound normal? i'm not using any methods of boost control other than stock

 

I don't think it should drop off that much. How many miles on cat?

 

actually I think I found the problem, my boost gauge reads ~2" of vacuum when it's off and 20" of vacuum when I know it should be 18-19, so I think my boost estimates are off by 2psi as well

 

My car always did that with the stock cat until I got a boost controller, at which point it held 10 psi to redline.

 

the dropoff to 8psi is normal

 

^ Yep. Perfectly normal and how it's supposed to work.

Bone stock the boost pattern is 10-8-10 until about 6500 when it drops to 8 again. The ecu bleeds off a little boost at high rpm.

You never hear it mentioned but in fact the stock boost pattern is 10-8-10-8.

 

damn indecisive boost

 

Mine did that too but it would drop around 5500-5800 rpm. It wasnt caused by exhaust restriction either... The stock ecu was consistantly dropping boost to exactly 8psi at those rpms. I patched into the wastegate control solenoid and monitored the pattern. Like rynberg, when I switched to a boost controller and took the solenoid out of the equation, the problem disapeared.