My friend has a third gen and I'm trying to help him out here. Whenever he starts boosting the primary turbo goes to 10 psi and where the secondary turbo comes in at 4500 rpm, the boost drops to 8 psi and then to 6psi instead of back to 10 psi. Is this a common problem? Any ideas of where to look or why it's doing that?

 

is the second turbo spooling up ? look at the secondary trubine and look for oil, also check out the main cat run the car hard then see ifts its glowing red, your cat might be plugged up, and if he doesnt have a downpipe i woudl get one