I'm wanting to do a 5/16 plenum spacer.
my question is will it help my gas mileage as much as the add says now I don't want to go to crazy on mods just something small.Granted it has 227k miles on it.But right now it idles and drives great. I got a deal..my first g35..
thanks

 

I did that years ago and the MREV2 lower manifold mod and it did make a difference at first, mileage went down. Why? I had my foot in it all the time. As the novelty wore off, the mileage came back to normal.

 

I didn't really notice any effect on my mileage. However, once I had my car tuned I picked up about 1.5-2 mpg highway mileage.

 

Which manufacturer is claiming fuel economy improvements?

 

^^^
I got the motordyne 5/16 and dont remember them ever stating it would help MPG

 

^^^ this