I got my miata back after a new radiator was installed and new cooling system hoses. I drove it, let it warm up, was monitoring the fuel pressure, in 3rd gear at fuel throttle i was spiking to 15 psi and 5k rpm. I have the boost gauge connect to the vacuum line for the cruise control, so I'm not sure if the problem is in the gauge. Any ideas I'm gonna call begi tomorrow....

 

I have the shanghi kit, only supposed to boost at 5 - 6....

 

Then your wastegate could be fucked. Just to double check try connecting your boost gauge to one of the ports in IM and see if it reads different. If not the your wastegate is stuck close or something.

 

You may have to grind down the top of your DP flange. A leaky hose going to your waste gate. Mine stuck open once, but never closed.

 

what exhaust you running?

 

Was it doing this before you took it to the shop?

 

i never boosted it was over heating so I assume it was. How do i fix the wastegate problem?

 

How tight(short) is the wastegate rod/arm? Disconnect it from the wastegate actuator lever and lengthen it.
Does the wastegate lever move freely? It should have almost 90* of range of movement.

 

How many G's are you trying to boost?

 

I think he's trying for audi 5000 G's.

I have the same kit and like someone else posted, I had to file down the top of the flange at the wg because the gate arm was rubbing. I never had any issues with overboosting but I filed it down before it was even on the car so idk?

OP, do you have any exhaust leaks where the wastegate dump pipe is welded to the dp flange? Mine has a few pinhole leaks around the weld there.