It would surprise me if you did any damage to the motor.
Once the singer has done its job, placing a straight through silencer should have little effect.
Here is an excerpt taken from.
two stroke engine tuning
Expansion chamber
When the exhaust port shape is decided from time area targets etc. we can dimension the exhaust pipe header diameter. This is critical to the pipes blowdown efficiency and the pressure build up. We need to pressurize the pipe with a strong and not too short pulse and the length will interact with the pulse resistance to create the necessary pulse shape. This means that it is not always better to use a diverging header (L1), sometimes a diverging header may result in that the cylinder exhaust evacuation is too rapid and causes the pipe to ‘loose the breath’ during the stroke. It will gain power at high rpm but lose in the lower range, mostly okay for race engines though. The phenomena needs to be viewed in a simulator to be fully understood.
bimotion pipe
To simplify some we say that the first diffusor (L2) acts in the lower rpm range and the last diffusor (L4) in the upper range. The rear baffle (L6,L7) angle decides the top end rpm range and power ‘hit’. Steeper angles will increase the pulse strength and decrease the pulse length, i.e. shorten the rpm range at which the usable power is produced. The internal length between the diffusors will also decide the power production characteristics, so if the first diffusor is relative long then it will gain power in the lower rpm range etc. A pipe that is pressurized with an early opened port (long duration) will be able to retain the pressure through the steep angles and deliver a strong suction pulse back at BDC. With strong pulses engaged we don’t need too large/high transfer ports. The pipe will then help and pull out the gas from the crankcase, even manage to open the reed valve and pull more air through the engine. When the transfer ports are closed, a second returning wave in the pipe pushes back the fresh gas that was spilled out into the header, in the remaining blowdown window that is. The charging pressure is often in the region of two atmospheres (bar) and far over that.
This is why the pressurization of the pipe needs to be well investigated together with the exhaust port, we simply cannot fit any pipe to an engine. It have to fit the exhaust port and even the transfer ports too!!
Finally, the stinger need to be large enough to let the engine breathe. A small stinger diameter (and long stingers) will increase the internal pressure and power but also make the engine run hotter. The length becomes critical to pulse resonance over about 9000 rpm. At that point the plunging effect at the stinger end will interact with the pipes internal pressure and help to lower the evacuating pressure at piston BDC. However, for high rpm engines, the stinger in general needs to be smaller than on low rpm engines. High frequency pulses have shorter wave length and will fit a smaller pipe better. But since the high rpm engine also needs to breathe more this can often even out.
