Baofeng GT-3TP power question

This radio of mine has selectable output power: 2, 4, and 8 watts. Anyone have experience with using an antenna amplifier with this radio? Its input range is 2 to 6 watts, with a maximum output of 40 watts.

My issue is I don’t want to overload the input with 8 watts if it could damage it, so it’s kept at 4 watts which results in under 35 watts output. I want the full 40 watts, so…

I’d like to know 1) if there’s a way to mod the radio so it puts out 6 watts, or 2) if inputting the full 8 watts would possibly damage the amplifier. (It’s a Retevis RF Radio Mate.)

I want to get the most out of this rig, so any (experienced) insight would be helpful. Thanks in advance.