I got rid of the overboost protection solenoid (ops) on my 300D about 9 months ago. After getting rid of it I tested the boost pressure and it only goes up to around 9 psi when I have it loaded up. That works fine for me and I have not had any issues.
If you want to keep it in working order you should check out the pressure switch. You should be able to find it somewhere on the intake manifold - it has a single wire attached. Try disconnecting it and see if it allows the ops to drop out. If it does then you have a switch issue.