MOTORDYNE 1/2" ISO THERMAL PLENUM SPACER FX35 350Z G35 M35 MOTORDYNE 1/2" ISO THERMAL PLENUM SPACER FX35 350Z G35 This stealth modification adds 12HP-14HP. The 1/2" plenum spacer outperforms the competition and is used for maximum performance enhancement. It also adds a substantially deeper induction growl under the hood. The engine cover WILL need to be modified in