back to the original question- "why a aftermarket can"??
here are some reasons
1.lighter. my staintune is 2kg lighter than the OEM unit.
2.more power.4-6hp from a slip on (my staintune) more from a full system.PLEASE NOTE that depending on the zorst, and the tuning/carbies/jets/EFI/power commander this can be raised if tuned correctly.
3.linear power delivery.often u can iron out any flaws, and get better midrange etc
4.looks. its bright and shiny-ish..it needs a clean.
5.sound. it DOESNT sound like a strangled sewing machine.
6.cheaper.If i had damaged it in a crash, its abt half the price of a OEM can. Tho some (yoshi's etc) can be closer to the cost/more than the cost of OEM.
7.personalisation. my bike isnt a stock unit.
if they werent better for power etc, GP and SBK boys would have stock cans...also ne1 remeber Colin Edwards vtr-sp2?? took the twin pipes off & just put a single on it..less weight, more power, better power curve...
then again i wouldnt throw any $$ on a 250..id save it for riding gear, or a new bike...