I have one of these, and it also came with the 2 extra tanks. I plan on using the original and fixing the leaks if it has any. I briefly tossed around the idea of using the original big tank, with one of the smaller tanks in front of it in next compartment, but then figured the CG would change as that tank would be ahead of the CG point. I will run her with the original.

I haven't even checked it to see if it leaks yet, I just finished building my kit Sonic 120 turbine.

Good luck with it and post how you make out.