Well, now you guys are pretty close (for the year 2015, the limit goes up very slightly in later years and the tunes the engine will tolerate change slightly, but that's a technicality).
- A cam profile of 100 doesn't necessarily yield the most power
- The larger the compressor, the higher the top end boost, which you want
- You just have to find the right size of turbine to match the compressor
- Then it's a simple matter of balancing the compression and the injection timing
If you want to know what the real limit is, it's very similar to the engine I put in my bus (see the Pikes Peak challenge in the challenges section). That engine was built in b1418: there may be a difference of 1hp either way in the Steam release.