How to increase the voltage gain in a Class AB Transistor
If you want that large of a signal swing at the output, you need a better way of biasing TR3.
I would start by splitting R1 into two 120k resistors, and connecting a 10 µF capacitor between the center node and ground. This will preserve the DC negative feedback for the bias, while eliminating the AC negative feedback that's killing your gain.
If that doesn't work, a more elaborate bias circuit will be required.

Also, if you want to drive a 16 Ω load with that much voltage, you're going to need a LOT more current gain in the output stage.