Should my stock silencer have 3 small 2.5mm holes drilled in it?

[Whitey]

I’ve just taken the diffuser off to get rid of 2 years worth of leaves
, grit and other debris and I noticed the underside of the silencer if very sooty as is the silver heat protection. Having wiped the silencer clean I could see 3 small drilled holes, started the engine, and sure enough exhaust gases do come out of the holes. So, is this normal, and what’s the purpose of them?

 

[brainf18]

Yes...these are drain holes to allow condensation to drain from the muffler

 

[Whitey]

Thanks, every day’s a school day !