It's the Fujita F5...and I think my MPG went up a little. But I'm heavy footed. Just got back from houston an averaged 20mpg. I had the Stillen Z tube and intake and I can say I have no ill effects whatsoever...ran open element on my EVO IX, GTO, and S4...moral of the story once it's hot heat soak is an issue for anyone. I wanted to spice up my engine bay and disregard any naysayers...tons of Z's run them.