Trying to make a little sense of this only having been given a bit of info just now.

My partners GTI was playing up/running rough yesterday and the exhaust system check light came on. She'd taken it to the mechanics today and they've said two of the cylinders need replacing (going to replace all four just to be safe). Unfortunately that's all she could remember the mechanic explaining to her.

The car is an '08 model, 75,000k's, always filled with 98, always serviced at the set intervals and she never pushes the car to it's limits. I'm at a loss to why she'd have a major engine problem like this before the car has even gone through it's first clutch change?

Is it a common problem with this engine at all?