That pre/post meth difference is amazing. Would you recommend meth on any DI engine? Is it ever too late to throw meth on?
The mileage is also great. What are you averaging with that car?
For meth injection to be effective (for valve cleaning), it has to be sprayed frequently and I suspect it is better at preventing build up then removing stuff already caked on. Is it worthwhile for any DI engine? Depends. As the deposits build up, peak airflow (power) will be reduced but, how long it takes to reach, say, 5% reduction? 100,000km? Is the reduction which happens at the upper RPM range, important to you?
For fuel mileage, with 83 fill-ups, the average is 7.95L/100km