erm wont that be loud?
from what i understand,u put a valve after the extractor during the long pipe section and the configuration should be open big while accelerating and close(not 100% close) for top speed.
this is bcuz bigger outlet gave more acceleration and smaller outlet creates more preasure(back preasure) thus giving more top speed to it(i think most of us know this)
well my bike have this valve,its called EXUP,and it does work well bcuz my bike is high revving bike,around 16k redline so in town the down low power is managable but after i tried my fwens bike,which he took out the valve,the power down low is worst but he dont mind cuz he dont do city riding wit it plus u can always slip the clutch to higher revs,well thats how my bike's valve work la,should be almost the same wit urs.
plus it can save ur petrol if its set to the right configuration
heres a picture of my fwens bike with exup,it has short pipe but valve is there to mimic long pipe preasure,well this is not exactly his bike picture but same model,so basicly u get the idea,and ill post my bikes exaust system.
well this is the rev,20k its tuned for high rpm running
well this is the short exaust if u can notice,theres a valve in the mid pipe to mimic longer exaust as i said
and this is the valve,the white circle is the motor to control the valve or named servo motor and the red circle is the valve actuator,and the way it move if im not mistaken is depending on the throttle,it will go adjacent wit the throttle twist im im not mistaken,this thing toooooo many electronic,even meter dun have cable,digital al the way,and if u put a transistor at the servo motor to make it open all the time to save money rather than buying rm12k fullsystem the meter will come out error code and ur meter will go crazy,so basicly do it properly or ur car will run like $hit
hope that will help,hopefully thanx,ciao