Has anyone ever added cold air induction to a non-turbo 850 sedan?

If you tinker with the induction system on your 850, unless it has some parts missing, you will probably make the car perform worse!

Our '96 855R has an air intake in front of the radiator as Ray mentioned. It is only about 2" by 4" and the car hauls butt!

I think that Volvo spent some time desigining a system that works. The size and length of your intake and exhaust systems are quite important to your engine's performance.
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96 855R, 95 855,854, 90 744 Ti - 340,000 Volvo miles put on 7 bricks

Isn't the stock setup cold air induction? It draws air from the
front grill. The cold weather package adds a splash shield right
at the front where air comes in. Removing that (if you have it)
might help airflow a bit.

You absolutely don't want to remove the cold air splash guard in front of the cold air intake. I was very careless one day rinsing my car with a hose and blasted water upward through the grill from below and managed to pump a goodly amount of water into the induction opening. The car ran rough for quite a while, until I suddenly got smart and removed the air filter which was soaked and had a puddle of water at the bottom. Once clean and dried the car ran perfect. I think this is why they installed it on later models. The guard will prevent water getting into the intake when you're washing or driving through a storm or having a sheet of water laid on you by a passing semi. Dick