Just stay at 15, with the way things are going youll probably blow it up if you go higher. Do you have an afc or a logger? If not, thats what you should concentrate on next. You could run more with that pump and 450s and be fine if you knew what you were doing.
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FOR A WOUNDED MAN SHALL SAY TO HIS ASSAILANT
'IF I LIVE, I WILL KILL YOU. IF I DIE, YOU ARE FORGIVEN'
SUCH IS THE RULE OF HONOUR.