Keeping the heat in the pipe does promote better exhaust velocity, however that usually only applies to high velocity exhaust components like headers and turbo down pipes. I do not see any advantage of wrapping the actual exhaust piping on these cars.
2012 Race Red 5-door SE, 18" Ti wheels, Ti headlights/fog bezels, 20% tint, debadged trunk
2002 Sonic Blue SVT - supercharged (sold)
2008 Vista Blue SE (gone)