i was just wondering how much HP going from 346ci. to 370ci. would make! Same cam, compression, heads, Intake manifold. Just more displacement. I have a LS2 block sitting here thats ready to accept 4.030 pistons, just drop them in and clearance them

 

I think your static compression will increase by about 1/3 of a point if you put the same heads on a 4.03" bore compared to 3.9".

If I had to guess on your gains I would go with about 9% increase on your whole torque curve. If your peak torque was 380 it might move up to 415 or so.

 

You will definetly gain more torque than horse power. I would hope it would gain 15 hp though.