Which option is more effective, replacing both plenums with the Kinetix or adding a plenum spacer? The Kinetix is a lot more money so I'm wondering if it's worth it.

 

Depending on which year G35 you have I would go with the MotorDyne spacer. The 5/16" isn't visable and you can keep your OEM engine cover.
It's the best bang for your buck and probably one of the best mods you
can make for performance with breaking the bank!

 

Welcome to the forum. First off, If you locate the search tool on the main menu at the top of every page, you can find most of the answers you are looking for.

Read over these three threads I started way back in the day about this:
https://g35driver.com/forums/intake-exhaust/123283-1-2-md-spacer-kinetix-plenum-final-answer.html
and
https://g35driver.com/forums/archived-sales/122904-feeler-switch-kinetix-aps-crawford.html
and
https://g35driver.com/forums/showthread.php?p=1487784

I've tried both and I stuck with the Kinetix plenum.

P.S. There are two types of Kinetix plenums on the market. The V series and the SSV. The SSV is strictly for looks if you're not running forced induction and may even lose you HP if you're not FI. I am running the V+ series currently and love it. I've also had the V and the V+ definitely has improvements over the V.

-Tom

 

Either a plenum or plenum spacer will definitely gain you some power. It just depends on how much you want to spend and whether or not you care about under the hood looks.

 

Thanks for the feedback. My intent is to gain power and increase the looks under the hood. I'd like to have a chrome plenum and z-tube with a half carbon fiber engine cover and Infiniti logo. With that said, should I just go with a spacer for the upper plenum or the upper and lower plenums, is adding the lower going to make a substantial difference?