A while ago I had a tune on my power FC for 200rwkw (stock injectors, stock turbo). A year later I had 740cc injectors put in, along with a high flow turbo. I then tried to drive it un-tuned to the tuners. It was running like crap, black smoke was pouring out, it was spluttering and I couldn't go over 30km, it made it less then 1km before the car completely died. Flooded the engine, had to get a tow..
Not worth it.