Saving Old Seagulls

i'm very pleased with my new EFPC. it fits my new dinghy a treat, it also means i won't have to cut down my EFPWL which i've become so fond of. After a thorogh tank clean/repaint, new fuel line and gear oil changing exersize it started in half a pull. fantastic! It does seem even noisier than my EFPWL though, which has a cowl over its different type of carb the other difference is that there is a cast tube (almost hidden behind the tank) in the flywheel cover. What is that for? I notice that when they called the various models 'seagull 2' etc. there was a plastic tube looking thing going from the carb to, i suppose this cast tube in the side of flywheel cover. does the flywheel act as a turbo or something? i have also been wondering about the water injected exhaust tube, on some models, does this make them any quieter running?
and could i add this to my motor through on of the existing holes in the exhaut tube to shut it up a bit? im not willing to alter any thing permanently on it but if there was some later noise reducing component i could add, i would. any ideas anyone?
the clutch and anti weed prop make it perfect for the canals and rivers 'round brum.

The old 102,s have the exelent water injected exhaust...not sure what yours is...

Thanks for the reply niander.
Is the injector devices' water source the tell tale? does it blast in or trickle? and most important, I suppose, does it work? I have at last found where i have read about the tube thing coming from the carb (on the old forum pages). it turns out that it is a noise reducing thing. The rubber boot on the hatchback of the wifes peugoet looks very similar.... with
some fins added to flywheel may make it like a supercharerish thing. However there's a little voice telling me to 'leave it alone or you'll break it!'... I always ignored this as a child.

If its like the 102 it doesnt go into the exhaust but it muffles the exhaustcomeing out of the small hole near top of tube...is yours a square block?