So i have my Seat Leon Cupra for like a month or 5. It has a Golf 6 R20 engine ( engine code CDL, EA113 2.0T FSI k04 ). I was driving it on the autobahn in Germany, accelerating hard to 250 km/h, had to let go off the throttle for another car and when i went back on it, after a few seconds the power was gone and CEL starts flashing. didn't hear any pinging/detonation during the drive. Thought of a broken coil and limped it back to the garage where i work on saturdays. VAG-Com said misfire on cylinder 4, so replaced all 4 the sparkplugs and coil packs. when i screwed out the sparkplug of cyl 4, i noticed that it was in bad shape. After putting in new plugs an coils it did still run on 3 cylinders and it was still misfiring according VAGCOM. So pulled out the plugs and did a compressing test. ZERO compression on cylinder 4. Took a look with a boroscope and the exhaust valve looked broken, so it will be a head job what i'll need to be doing Any thought on what have might happened? My car was mapped 2 weeks ago, and my tuner ( a very respectable company over here ) drove more than 100 miles on the road and dyno and said that it was finetuned perfectly. Stage 2+ custom map, 367 HP/470NM Torque Autotech HPFP Audi S3 intercooler HG motorsport intake HG motorsport turbo outlet Miltek turboback exhaust with 200cells cat BSH PCV revamp kit Go Fast Bits diverter valve + Had RON100 octane in the tank, wich is the same as AKI -+ 95 Thought on this?