On the muffler? Mine do line up, which is why I think it`s doable. Mine`s already held open with a screw.

Well, we can put this one to bed;

if you are willing to cut the heat sheild, (or wrap the pipes) you can cut it out and slip the muffler straight back on.
- Can with my bike anyhow... 2011 Streetbob.

Just finsihed it off, louder also. - That valve has a massive surface area, even when screwed open.

You also have the option of buying (US e-Bay) some dealer take off 48 state downpipes.  That's what I have on mine - they don't have the flappy valve crap in them.

FatRob

ive been in the custom pipe scene since 1975 an seen the flaps in heaps cars an some other euro bikes the main reason they have the flap is to shut the gasses down so it restricts one pipe an makes the bike warm up quiker if any of yas had a red motor holden with the 6 pollution models mmm hz hx ect there was a flap in the exhaust manifold that closed when you started the car and would heat up the inlet manifold an it opend once the thing got hot enough .alot of the cars an bikes that are injected have some form of blockage flap in the exhaust so the motor gets to operating temp quiker an the computer starts to get the readings it needs once bike/car is ready to go .not bein rude but its got nuthin to do with noise in calif or any other place noise they sort with mufflers that why the catolytic convertors are nearlly always lower than the o2 sensors so the cato slows gasses an also gets an holds x amount of flow back so sensor can get its readin ...when they first bought out the xf falcons with unleaded catos an sensors we done heap tests on dynos ect an if ya take cato out the readin the sensor gets is the car was runnin at higher speed an the comp would dump bit more fuel in that why alot of vechiles get worse fuel economy after ya put the pipeson an remove the catos ect