Was not me.... I will definitely run some pretty thin rings in a race application. Usually calls for custom pistons - - an .043 top, an .043 and/or back cut 2nd, and a reduced radial wall
oil ring will free up some true measurable power - often 20HP or more.
I usually just run conventional 1/16-1/16-3/16 ring packs in street engines though. There is power to be had in fancier stuff - but its not in proportion to the added cost for most guys. Depending on the quality of the machining
oil consumption can be an issue - or it can actually be reduced. The custom pistons and swoopy rings will bump the build price by somewhere around $500.
No silicone in pistons
Many street oriented pistons will have silicon though - - it adds durability for skirt and ring grooves in high mileage applications (such as daily drivers). The racers usually use 2618 alloy which has greater high temperature strength - but no silicon. Its really a matter of the right alloy for the intended job. Most Cobras don't rack up enough miles for durability to come into play....