2014 BMW M4 standard factory exhaust sound have varies opinion from BMW enthusiast. Most of them love it but there also fans who are hard to accept the fact that the sound is not the same as it came from a 4.0L V8. It is because due to strict regulation and to improve fuel efficiency they decided to replace it with a 3.0L V6 engine TwinPower Turbo. Although it has a smaller engine capacity, it has a bit more power with 425 hp compare to 414 hp for 2013 M3.
For me personally, it sound great and good for your pocket too since it use less fuel. With twin turbo system, we can get enough power when we need it. In some country like Malaysia, you will pay less road tax due to smaller engine capacity although it is not cheap like other car but it definitely much better compare to previous M3 models. You can used the money you saved from paying the tax for a new carbon fiber front spoiler and make your M4 look more awesome.