Kipk - I'm not a tax expert but I'll give it a go. The tax man always has his hand out whenever there is a gain. You will loose roughly 1/4 of your gain on paper the day you take the profit. 

If you truly believe the share price is going that high consider doubling of tripling your investment today and sell a third or so of your position into strength as the share price rises. If your correct and it goes to 10 then you will have taken enough profit to pay for the entire investment, the taxes on the shares you sold and put just a little jingle in your jeans. Alternatively consider the WT.A's as they expire worthless in June 23 but give you leverage to the share price between now and then. The risk is losing all of your capital with either of these strategies if the share price does not do what you expect.

Maximizing the use of your TSFA would certainly help you pay less taxes in the scenario that you first proposed. The risk here is that you will have lost your tax free investment room if this high risk investment does not work out.

Other than that be a happy tax payer if you make some money. The key there is that you make money instead of taking a loss.

Seriously I'm hoping to have to pay millions in taxes because what's left over for me after tax is 3X's what I pay to the taxman.

AIMHO, dyodd and seek professional advice.

tada