0.45 mm is 0.018" which is perfect for 20-25% nitro as I read it.

Measure the actual squish clearance using a piece of solder. Take out the plug and insert a piece into the head and turn over the motor by hand untill the solder flatens between the piston and head. Then measure the thickness of the solder.

Dont stick the solder in too far and through one of the ports and loose a piece inside the engine! (as I did!)

My Pixy had 2 shims which i removed completly to have 0.020" head clearance.

I just reduced my NS3 down to 0.014" and a C5TGF Turbo plug as Motorman suggested and it has a lot more low end power with no loss of top end and slightly cooler running.

Cheers