Hayabusa OEM exhaust?

a stock busa will turn an 8 second ET in a drag race not so easily humiliated! As for the exhaust systems you hear usually a performance exhaust is used with an EFI remap for an added small amount of HP.

I have limited exposure to Suzuki's Hayabusa, In my limited opinion the exhausts shown in your link are OEM. The original exhausts are expensive to replace compared to after market. The triangle shape allows a maximum quieting effect and still allows added ground clearance when the bike is pulled over in sharp cornering.

Some change the stock exhausts to after market for more performance but on a motorcycle that only has to have the 300 km/hr restriction electronics removed and replaced in 30 minutes and you can make it into the 200+ mph club it makes little sense. Less sense if it is done in public instead of dry lake beds under controlled conditions.

Adding a louder exhaust would only be considered a vanity addition. That addition of a louder exhaust would be very tiring on an extended distance ride.

Although the stock heavy weight bike is easily humiliated in a quarter mile run the added horse power could minimize the humiliation from a smaller displacement lighter weight motorcycle.

187mph =300kph It's a nice round number over there. Insurance companies were looking to drop sport bike coverage if manufacturers didn't stop the trend. Now we can still get around the manufacturer's controllers, for cheap, but that's another story. Ultimately, 187mph is an arbitrary compromise reached between insurance companies and manufacturers. Most riders have accidents below 70mph, and therefore more riders die from accidents below 70 mph. The 'sausage creature' can find you anywhere (Hunter S. Thompson in Cycle World 7/94 re: Ducati Monster) Accidents above 70 mph have far more lethal effects, but these riders must face the reality that it isn't the speed that ever kills the rider, it is the stuff encountered during unexpected deceleration that can make things messy.

Noise or the lack there of.

Some think louder is faster (and with the proper engine refinements it can be) but it's usually 'louder makes the bike seem faster'.