Help with first Subwoofer Project

Yes! this forum is exactly what I need!
Hello all!

I would like to start on my first Subwoofer project, it's a 180W subwoofer system for my room, I have found an amplifier kit and a subwoofer from Jaycar Australia but I have forgotten one thing which will prevent this thing from working properly.

Here are the components I want to use
350W Amplifier Kit

Toroidal 500VA

12inch 180W 4 Ohm Subwoofer - Double Magnet NOTE link provided shows 15" not 12" but very similar

Making the amplifier should be easy and connecting everything up too but one thing I spotted is the transformer only gives 5amp which I think isn't enough.
I use to have a car amplifier and 12" subwoofer set up in my room hooked up to a 25amp 12v power supply, and with all the settings on the amp set rather low it used up about 20amp.

I would like to know if their is any way to increase the current for this toridal, I know in car audio when the car isnt just giving enough current you can use a Cap usualy rated at about 1 Fared and this usualy helps, is there any way I could do this with my idea?

I'm also planning on making a crossover for the subwoofer to give me around 55hz which is what it reccomends in my jaycar catologue.

Any help would be greatly appreciated!

P.S I have built a 20W amplifier before and also made some speakers for it too and it all worked nicely, I guess what I'm saying is I'm not a newbie to all of this