I was messing around in my box of spare parts looking for something, and ended up finding installation instructions for a MD plenum spacer. I went and checked and my car, and BAM, somewhere along the line of the PO's, one of them installed a spacer. However, I was curious if the MREV2 mani had been installed as well. I am not looking to take off the upper plenum, but I did notice something after googling. My lower intake has a "casting tab" with a 5 stamped on it. I am fairly positive that it's only on the MREV2 mani's, but I could be wrong. Is this a legitimate way of knowing its an MD product, and is there any way to be 100% sure without removing the upper plenum?

Picture for Reference

 

No, the MREV2 is just a modified OEM non-Rev lower plenum so both will have that tab. In this photo, you have an MREV2 on the left and a Rev-Up OEM plenum on the right.

 

But, if you have that tab it means its either an mrev OR a non rev-up lower plenum. The non rev-up plenum works almost as well as the mrev, so if you've got that tab you are good to go whether its mrev or otherwise. Really you just don't want the one on the right.

 

I thought the MREV2 and the Rev-Up mani were similar in gains. Unless I'm comprehending your statement wrong or you mis-typed it then I would be better off with the stock mani that came on my motor since its Non-Rev. I'm not calling you wrong, but from the MD site and other peoples tests, I thought the MREV2 and the Rev-Up were basically the same. So just some clarification would be great. The tab means I either have the MREV or a Rev-Up mani?? My car is an '03 so its Non-Rev. Right?

Edit: Nvm, found some more info. I see the difference between the Rev-Up and Non-Rev. But the Non-Rev mani would have came stock on my car? Sorry for the noobiness. I'm so damn confused...
Link im looking at for reference. https://g35driver.com/forums/engine-...er-plenum.html

 

Yeah, yours is a non rev. You don't have to worry about a lower plenum.

The only one you DONT want is the rev-up plenum. The Mrev is an 03/4 lower plenum that has been modified for any car that came with a rev-up motor.

Basically, anything other than the rev-up lower plenum is good. The rev-up is flawed in design.

 

well... wasnt the revup designed with shorter runners to help with gains in the upper end of the spectrum. im pretty sure it beats out the non revup plenum in top end gains. also why the turbo guys run em if not running a cosworth or other huge plenum

 

The mrev does flow slightly better than an unmodified nonrev plenum, but not enough to spend $500 on. The mrev is basically a ported and polished nonrev plenum. I saw a thread on my350z where a guy opened the runners a bit and ported and polished it and Tony from MD commented on the thread saying the other guy was very close in terms of how an mrev2 is modified. So, yes, if you're turboed and need MAXIMUM flow I would go with an mrev (or port/polish my own), but for NA, any gains would be next to immeasurable on a nonrev VQ.

 

I can confirm. Borrowed an mrev2 from my friend before he installed it. But it on. Yes amazing! But did a non revup lower plenum. Legit no difference. If you did it while I slept I couldn't tell a difference

 

i am confused at your wording. the mrev and mrev2 are both ported and polished nonrevup plenums. i was talking about the actual revup plenum with the shorter runners. not the modified one from motordyne. because in the pictures the op is comparing the mrev2 (non revup plenum) to the revup plenum on the right with shorter runners. the revup plenum (on the right) is supposed to flow more at top end compared to the nonrevup or modified mrev2 plenum. i am assuming the longer runners on the nonrevup plenum increase the air intake velocity from the longer runners but that would be pure speculation

 

When I say mrev or mrev2 I'm talking about the MD product. Not sure where the confusion lies.

Bottom line:
Rev-up plenum - not desirable at all
Nonrev lower plenum - fine for all
MD mrev2 - slightly better for rev-up motors than nonrev plenum and optimal for FI applications.

 

^^^whs

 

lol yes. if you read the original post i had written where you responded i was saying the revup plenum is actually desirable for top end. comparing the nonrevup plenum to the revup the revup will flow more for top end. the turbo guys run the revup plenum over the mrev2 or nonrevup plenum to flow more for top end