Originally Posted by RambleJ
The only reason the Audi S3 has quad tips and its a 4 cyl is to keep up the S line appearance. Its a cosmetic feature.
My point exactly. Quad tips are used mostly as an aesthetic feature.
Every "true" M car has quad pipes now; the 1M, M3, M5, M6, X5M and X6M.
The 1M has a 3l engine with 340hp and doesn't need quad pipes that flow the same volume of exhaust as the 4,4l M5/M6 560hp engine. Dual tips would have been sufficient (the E36 M3 has 321hp and manages with dual tips...), but for aesthetics quads are used.
To quote the official press release from BMW for the 1M:
Last but not least, there are the obligatory four exhaust pipes on the back
Meaning that the 1M has quad pipes, not because it NEEDS it for engineering reasons, but because they are now deemed obligatory on an M car.
Some have argued that that feature is only acceptable on certain engine configurations
... Like it's ok on a straight six E46 M3, but not on a straight 4 (like the 300hp Audi S3). Go figure the logic