Just installed plenum spacer on my non rev up 350gt or g35 for others. I don't know, I feel like I've gained nothing from it?? Almost lost power. When installing I forgot to remove the guide pins.. I am running two bolts short in those two places. When installing I torqued to correct specs and silicone sealant both sides of the spacer using the original gasket aswell. My Idle sits around 600rpm down 150 from b4 the install. Do I have a leak? I would pull the spacer off and replace the guide pins except the spacer is sealed down on both sides with sealant and would create a mess and so on. What do you guys think? Is it just in my head haha.

 

Will note. I haven't taken the car above 5k rpm... Don't really like going much higher... Just bought it hence being careful.

 

Borrow or buy a $10 vacuum gauge and hook it into one of the small hoses on the intake. Usually a vacuum leak will cause the idle to surge up and down. Did you remember to reconnect the hose underneath the intake snorkel? Gl.