HHhhhhmmmmmmmm....... I'm looking at the ECU for the open pipes as we speak. It's stamped :

999 RSARACING for OPEN.EXH PIPES ECU 999/03

Now I have the full 57mm Termig system with appropriate ECU fitted and the above mentioned part was the only ECU given back to me after the fitting.

I also had a hestitation issue around 4,000 RPM on the un-cat pipes but no problems with the big system at all.

Point is I don't have an ECU for the CAT system so both systems are in my garage with just the one ECU