Doesnt sound too bad.. I would imagine combined with a SRI or CAI it might make more (not counting the HP the SRI-CAI make alone) due to the increased incoming airflow?
I had an intake before I did it. so probably not. Though I only did a 2.5testpipe and some do 3inch. I think with a stock dp though a 2.5testpipe is best.
I did 247whp/281wtq with an intake and test pipe. I didnt have a dyno from before the test pipe, but I would guess more low end torque and maybe 5whp/15-20wtq. But it's hard to guess since all dynos are so different.