Hey gang,
I have a 1990 z32 TT with roughly 160k.
since I got it I did the coils, timing chain, brand new oem engine harness, new clutch, etc.
the car is about 85% stock.

Recently, I changed the fuel injectors to 555 cc for a Z1 ECU addition. There were various setbacks including issues locating the right fuel injectors, a now resolved knock sensor in cylinder 6. I got the car back and it runs fine at low speed/low RPMs. However there is a note able decline in boost at higher RPMs so much so that it adds several seconds to 0 - 60.

my mechanic says the fuel is flowing much more freely now as expected...too much. So he recommended restricters to correct the boost problem.

my questions:
1. Shouldn’t the ECU be regulating this boost issue?
2. If not, are restrictors the answer or is there something better, easier, lower cost to address this?
3. Is there additional tuning involved that perhaps my guy isn’t up on?

my mechanic is a Nissan certified master tech for turbos and diesel and has sole responsibility over GTRs, Z cars, and all of the more complex assignments.

Thanks in advance for your help!