Hi guys! looking to upgrade my 04 FAST! it came with exterior and suspension and brake upgrades. i've ordered the stillen Z-tube and CAI. i'll soon be ordering the stillen cat back, as well. now, to the question.... the plenum spacer (Motordyne) - 5/16" or 1/2"? OR, should i just replace the plenum all together (MREV2)? can i do both?!?! i'd really like someone to shed some light on this for me. i've noticed that a lot of the coupe guys use the 5/16". why? space issue? the 1/2" gives you more. thanks in advance, guys!

Spend some time in the technical area, especially the intake & exhaust section. A good supplement is also the Intake/Exhaust section over on my350z.

Like I mentioned in your other post... there is a bunch of info on this if you use the search feature... however it won't be all in one nice tidy place. For that reason, here�s my .02:

You definitely do not want both spacer and after market plenum. One or the other - personally I feel the spacer is as good or better choice than any of the after market plenums and cheaper.

The MREV, and MREV2 are not upper plenum (as you implied in your posts), they are the lower collector (the bottom part of the plenum) - since you are 04 it's not really advantageous to have both but you could if you choose to (you probably won�t see much more gain with both than one or the other)... As for 1/2" vs 5/16" it's your call - with 5/16" you will see a little better low-end gains, with 1/2" a little better high end � it�s so moderate you can�t really say one is better then the other. The 5/16" will allow more clearance if you choose to keep the engine cover on - most that have a spacer leave the cover off or use 1/2 cover (like a Z-cover)...

In all cases get the Iso Thermal kit to help keep plenum temps cooler. There are 2 choices, a manual valve that you open and close with a lever (earlier models require screwdriver) or the copper option that automatically opens and closes depending on ambient temps. Generally if you live in cold climate you want copper so the coolant flows through the throttle body chamber to prevent freezing... if you are in warm climate get the manual valve since you will rarely if ever need to open it (I'm in So Cal I've only opened mine once and probably didn�t need to). This kit (both versions) also includes a thermal gasket that installs between the lower collector and the manifold. If you put your hand on your plenum stock it will be too hot to the touch to leave it there... with the Iso thermal kit you can literally keep you hand on the plenum - it's warm burn not scorching hot - just helps keep intake air colder.

There's probably more - but that's the basics... since you seem to be in a hurry with wanting to mod I figured I'd throw it out there... But EVERYTHING you want to know about basic mods are out here and on my350Z... just take some time to research and you'll make good decisions.

Happy modding!

Edited with corrections and a little more info

when you said 5/8" did you mean 5/16"? just want to make sure. i'm looking for low end power due to the extra weight, sedan and all.

i've combed SO MANY threads, posts, and forums! everyone has a coupe. that's why i was posting in this one. not as many people upgrading the sedans.

i'm looking to beat the stock 350s and coupes. LOOKOUT!

You're mis-informed.

The G35 Sedan, G35 Coupe, and 350z are identical when it comes to engine. Both are catagorized as either Non Rev-up or Rev-up, depending on whether your 05-06 6MT or not.

A stock sedan has the same exact potential as a stock coupe.

.

yes, 5/16"... I was trying to cram so much in such a hurry I don�t know where the 5/8" came from (ratchet on the brain or something)... and the sedan is actually lighter than the coupe so you already have a bit of an edge here.

As skaterbasist stated we all share the same motor so all mods are interchangeable� You have a non rev-up motor, which is where MREV2 or 5/16� spacer works well (both for rev-up).

I have an 04 AT sedan with MD Iso Thermal �� spacer, Stillen CAI, thermal coated Z-Tube, ECU re-mapped and a few other minor tweaks, as well as minor suspension mods� trust me you can get your sedan to do just fine against coupes and Zs.

Just read the post in the proper threads and you�ll learn a lot!

looks like it's gonna be the 5/16" for me!!!! i've learned more from you guys than i have trolling for hours. thanks again!!!!

you're welcome... I think you'll be happy with your choice... however, it's had to avoid the mod bug once you get started

Happy modding!

Good choice, the 5/16" is better IMO for most people.