Heads Johnson 115.

Hello, i am new here and hope someone can answer my question...i have a 1998 115 Johnson Oceanrunner, this engine is fully rebuild.
We have 95octan pumpgas here and my question is how mutch i can cut the heads, i want a bit more compression/torque.
I have build my own raceengines for 20years but never did porting or other tunup on outboard engines so if someone can answer i hope i not need to calculate the chamber volum/compression ratio.
Sorry about my poor english :)

If you do not know your current compression psi, you are just guessing.
If you do not get a response from anyone here, what I would do is test for compression, then remove heads and bring them to machinist to cc them. Just my .02

Due to the dome in the piston you cant just cut them you need to recut the squish as well. Also depends on what it is pushing.