If you have the crimp style connectors with the GMTU I'd check those. I replaced the stock BPV with a Forge unit and it made no noticeable difference in performance nor fixed the surging issue at steady throttle. Fixing the connectors solved the problem. The issue is intermittent so difficult to diagnose but a quick jiggle of the lower harness was often a quick fix albeit temporary. VERY frustrating I might add. Learned all about crimp issues while quality control at a Jaguar store. A quick pinch with some pliers on the right connector and problem solved, for now...

 

Just the kit...2 sensors and wiring and tune come under the 1 year....( only the changed parts) The rest of the drivetrain is still under 100k warranty...so the bov would be covered...and besides they cant blam,e the kit when THEY made the kit!