I noticed sometimes (or usually) when i accelerate hard, I hear this metallic/rattling noise at around 4-6k. Is this normal? I first started noticing it after installing mrev and spacer. I removed both, but it still makes that noise. What could cause this?

I posted this on G35 forum also (i have a g35), but no one has responded.

 

How serious of a noise are we talking? I would be willing to bet what you're hearing is the suction from the intake. I wouldnt have removed your spacer and mrev though.

 

just a fairly audible rattle that can be heard coming from the engine at WOT..I know what the intake sounds like, but this sounds more like a resonating as the engine hits a certain rpm

 

theres no normal metallic tapping sound.

I cant think of anything that would cause the problem related to the recent spacer install.

At best the only thing I can think of is the bolts to the plenum could possible be rattling under load, although you would experience other problem for a loose plenum, its still something worth checking

 

Check your bolt torque. Sounds like you have a vacuum leak causing this. Mine did it too. How's you idle?

 

did you drop your bolt in the intake housing or anything.

 

well i torqued it by "feel" cause I didn't have a torque wrench, but I just bought one, so now i'm going to retorque and see if that fixes it