While titanium retainers do lower the mass of the valvetrain, I was always told that they're more of a racing only application as they tend to wear rather quickly (15k mile replacement). I may have been misinformed.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine