Loss of boost pressure. HKS GT-RS

[CrazyInteg]

I had my ECU modified so I took the 240 to the dyno to adjust the fuel pressure. I was hoping for some gains, but every time I get the car dyno'd it has less and less power. The boost spikes around 4k RPM to 26psi, and drops to about 19 psi by 7800 RPM. It has always done that. The mechanic thinks it might be the internal wastegate. It should be running around 24psi all the time. Obviously the mechanic wants to make money and just suggested a new Garrett turbo instead of trying to fix the GT-RS.

Any ideas why the pressure would continually decline? Can that be fixed?

FYI, last year the car made 300hp, and this year with the updated ECU it made 280hp. Both ECUs were/are RSEnthalpy ECUs. Last year the car spiked at 28psi, and worked its way down to about 22psi.

[180fan]

I'd take a gander at the wastegate as well.

[CrazyInteg]

A guy on another forum is telling me that my Turbo XS manual boost controller cannot really handle that much boost. He is recommending changing the boost controller.

[180fan]

hmm better description of your setup. You didn't mention a mbc.

[CrazyInteg]

hmm better description of your setup. You didn't mention a mbc.

I have the Turbo XS high performance manual boost controller, HKS GT-RS turbo, HKS adjustable wastegate actuator, RS Enthalpy ECU, front mount intercooler

The mechanic said the car has always done this since the day they built it. (I'm the second owner)

[180fan]

pull the mbc from the loop. i'm pretty sure the hks actuators won't function all that well at high boost like that. Post back your findings.