That one is a 350 Chev, built flown and owned by Jim Wickham of Tyabb, Vic. It's a 3/5th scale.
He also has a single seat Spitfire with Jabiru 6 cylinder.
The other one that you might be thinking of is the Titan Mustang.
www.titanaircraft.com, it's a 3/4 scale Mustang, gross weight 56 kilo's. Finished cost around US$70 apparently with Rotax 912s. 130 knot cruise. I suspect Jim's aircraft is quite a bit quicker than that.