I'd say a completely stock ST4 should see about 100 to 105HP at the rear wheel, and maybe 65 to 68 lb.ft of torque.
Look here for 916 curves
Here's a 916cc engine
with the complete DP kit, again maybe 105HP and under 70 lb. ft. of torque.
The ST4S model (996cc) gets you maybe another 5 or 6 HP
in stock configuration.
All the HP numbers quoted are using the SAE correction factor. Different dynos and different correction factors give you different numbers.