Low compression numbers due to valve, why?
 

Looking at a turbo, maybe.
Lower compression in one cyl. due to an intake valve... what would cause this, would it need immediate replacement?

What test was done to clearly indicate an intake valve as a problem?

Could be a scored cylinder/bad rings.

Burnt, cracked, or bent valve could cause compression to leak. I am not sure about the 944 valve train but a broken, collasped, or cracked valve spring could also cause this problem. Alot of carbon build up can also prevent a valve from sealing properly.

SoCal has a good point though it could be the cylinder/rings. I would also suggest a bad head gasket. Head gaskets seem to be a common problem on these cars.

It was a PPI so I'd assume the results were from a leakdown...

What exactly is a burnt valve? The car still runs fine, so I doubt it to be a bent valve... And wouldn't a bad spring cause real problems at high revs?

I have never had either problem so I am not sure, but here is my understanding.

A burnt valve is caused when the valve becomes too hot, and the heat causes the valve to deform.

Bad springs should affect an engine at any RPM.

Only the exhaust gets "burnt". This is where there is a small bypass at the valve (cracked valve seat or a bit of debris like a lost washer) and the exhaust gases scours a bit of the seat and/or valve. this grows till there is almost no compression on the cylinder.

A leak down will tell you real quick if it's the valves or the rings/cylinder wall.

Having an intake leak is very rare unless there is something stuck in the seat. Then there could be a bit of burning but most likely predetonation of the intake gasses resulting in some serious damage.