Originally Posted by TBSS2008

It is definitely not chambered like a flowmaster it’s straight through with an X pipe. I think the X pipe design with the large resonators really lowers the volume of sound without hurting flow. Y pipe designs like the Stillen seem to have more rasp when paired with a HFC or Test. The HFC and TEST pipes sound great with the Invidia Gemini, you will love the sound!

Best 370z Invidia Sound Video ever made:
YouTube - 370z Invidia Gemini Exhaust and ERZ HFC review

Check it out at 5:40 minutes in, great take off (Invidia, ERZ HFC, Stillen G3)