All four of mine replaced yesterday at Central SEAT Birmingham. VOSA letter arrived last week (after SEAT had been in touch).
Not noticed any difference in performance, MPG is slightly higher, and engine slightly quieter. Or maybe i'm just imagining it. Still waiting for the refund for the injector & loom i paid for in 2010 though.
Anyway, it is a relief to no longer worry about an injector packing up on the motorway and i trust the car a bit more again... last 12 months its always been on the back of my mind whether it will pack up in a dangerous situation. The first time was bad enough...in the middle of a 8 lane dual carriageway traffic light junction in rush hour!