Hi to all rx7 enthusiasts, I need your advise.

I have a 2002 Japan spec Rx7. Two months ago the car was running fully stock with no prolems but suddenly I got a boost problem. The second turbo was not engaging proberly and a strange whooo sound was coming out of the hood.

I bought a vaccum and pressure tester tool and start checking all things that needed to be tested. During this small investigation I have found that the main catalytic converter was not working so I have changed it and got a new one which is a high flow, the air filters have been changed from stock to aftermarket. And i have also found the problem of not boosting properly, the one way valve from the primary turbo to the pressure tank has cracked so I have changed that too.

At the moment the car is running like a rocket when the second turbo turns on you feel that you are in a single turbo conversion. However, during the transition I get a strange sound that worries me.

During the transition from first to second turbo I hear a sound similar to the engine geting at top rpm and hitting the rev limit then suddenly the second turbo engages and the car runs as it should. I am not sure but it may as well be the first turbo surges or getting overboost due to the new high flow catalytic.

What shall i do to fix this problem ? I was thinking of getting power fc and boost coontroller do I need something else like porting the wastegates ?