Why don't all sport bikes have under tail exhaust systems?

[Yuuup23]

What are the pros & cons of side & under tail (seat) exhaust systems? Personally always liked it under the seat better & Ducati does it under the seat & they make some great bikes

 

[WilliamBlowfty]

It doesn't effect my Honda but my arse gets very hot on my Ducati especially if I am stuck in traffic

 

[sleepy]

The aesthetics of an exhaust system mean nothing, it's the flow characteristics that determine it's efficiency for it's intended purpose.

 

[James]

It's a styling thing. It's not really practical: The exhaust system ends up being longer--and heavier--than necessary, it heats the seat, and you end up with no under-seat storage. It can also make it difficult to fit luggage, such as soft saddlebags. I much prefer Buell's idea of placing the entire exhaust system under the motor.