It was pre-ignition that killed my almost new rebuilt engine in the old celica GT4 (it had forged pistons, uprated bearings, head studs, metal head gasket). All the components were rock solid so it exposed the next weakest link which was the engine block. It cracked between the cylinder chamber and the coolant channels meaning the cylinder pressure when on boost forced coolant out the system and all over the engine bay (and windscreen when driving). Part of the problem was a clogged up inlet manifold air pressure sensor, so it momentarily under read the inlet pressure and so under-fuelled when coming on boost resulting in pre-ignition. The rest was a fueling system that didnt have the capacity to supply enough fuel on a particularly cold winters night.
Pre-ignition can be caused by all sorts of issues: Slight failure in the fueling (slightly faulty sensors, injectors, poor quality fuel), excessive cylinder temps, excessive build up of coke getting hot and igniting the fuel early, excessive inlet temps especially on a tuned car. A combination of all the above.
I don't know much about the workings of this engine but I would assume it has some fairly sophisticated protection systems. Its entirely possible that hasn't been working properly either. Even 20 year old cars with knock sensors were detecting pre-ignition and backing things off accordingly to help save the engine. Systems must have moved on since then.
From what I've read / experienced with the stock S3 interooler I dont think I would have any kind of tune without this being upgraded. It just doesnt seem man enough for the job even on a standard car during warm weather. It makes you wonder about tuned cars put on rolling roads during testing. Perhaps the inlet temps are manageable when the enormous blowers are blasting the intercooler on the rolling road, but what about when you've been stuck in traffic and then boot it with the intercooler having been heat soaked. I know from the older days of tuning cars that inlet temps are a hugely significant factor in the likelyhood of pre-ignition.
