These are used to add a turbulence into the exhaust system to combat boost creep often
associated when fitting De-cats and Full Exhaust system when using the OEM turbochargers.
Tested to add enough back pressure to allow a safe boost increased obtained when using an aftermarket boost controller. But still giving better power gains that if the catalytic converter was retained. Also tested to have no negative effects on power/torque or spool but allowing a manageable boost level.
These are essential for a J Spec supra running decats and BPU modifications.