How much did the exhaust cost? Did it make much difference to the sound inside the car? I am in China which looks like you are as well. The other thing that could do with improving is the mapping of the gearbox, while faster and more convenient than the V6 is can at times be caught out. I have driven both the V6 and the i4 on a race track and the i4 was much better around the corners and much faster (lighter, more powerful, more gears, better back-end etc) plus it is more convenient in big cities.