[ToySub1946]

Quite normal on any car with a muffler...on an internal combustion engine.

After turning off the engine, the dry, hot interior of the exhaust system pulls in moisture from the air...water vapor.

You may have noticed from the rear, a car just started cold. Water comes out of it's exhaust...the water which went in there after the engine was turned off.

Some mufflers may have a drain hole for excess water to exit...yet certainly not all mufflers.

And many mufflers have a fiber material within (muffler packing...designed to change the muffler's sound during engine running conditions), which can soak up water, holds it...until the later hot muffler dries it out.

You might question Invidia as to what they may use for muffler packing.