Can you run a turbo back exhaust system with 1 aftermaket Highflow cat??

[Guest FKADizzmystar]

and not over boost. i have J-spec Hybrids.

[Homer]

With a single high flow cat on a jspec you will need a restrictor ring to stop overboost, even with a single stock cat and a straight through cat back they can go past 1.2 bar in cold weather.

[Guest FKADizzmystar]

What are the diameters of a restrictor Ring