muffler or not? please advise

[ianmanning26]

i have a gx200
flat top piston stock bore
billet rod stock length
billet flywheel
4 degree advanced timing
removed spark plug boot resistor
rob torque tube header
22mm mink carb
265 mod lift dyno cam
uni filter
adapter
gov removal
fuel pump
18lb springs
stock valve train
14cc gx160 head, no milling, some porting

i dont have a muffler at the moment and i am pretty much done building the bike, will running a straight header with no muffler cause damage or loss of power to the engine? i am not concerned with how loud it is and neither are my neighbors, they are really cool and i let them ride all the time, im just wondering because i keep reading about how these engines need the back pressure that a muffler provides. i have an RLV style old muffler in the garage that i could throw on there if i need to, but if its not going to make the engine better then why do it? any help and details explaining the benefits of running with or without a muffler will be appreciated. i have searched and searched but the only threads i find are ones asking which exhaust is best for a certain engine. nothing that explains why or why not to use a muffler. thanks.
the bike is built just to be ridden on the weekends at moderate speeds, nothing crazy like drag racing.

 

[r_chez_08]

You will be fine with a straight pipe.

 

[joekd]

If noise isnt an issue then just the header will be enough

 

[65ShelbyClone]

1.)will running a straight header with no muffler cause damage or loss of power to the engine?

2.) im just wondering because i keep reading about how these engines need the back pressure that a muffler provides.

1.) Not with a properly-sized header, which I think you have. Jetting is also a consideration.

2.) This is a common misconception. Backpressure is just another word for restriction and restriction is the enemy of engine output. What happens is someone will install exhaust that is too large and that kills exhaust velocity where it most noticeably affects torque; the low and midrange.

Mufflers are there to control noise and little else, but they don't have to be detrimental to power. A straight-through bike silencer with the right inside diameter would work well with little or no impact on output. I think muffled singles actually sound better and my hearing thanks me for it.