Mrev2 is a intake manifold with slightly larger intake ports, therefore each cylinder can grab more air.

 

Ok. Thanks for the info!

 

MREV2 is a non revup lower collector than has been machined at critical flow points... the intake runners are longer (OEM) than the revup - the fact that it is MREV2 doesn't make them longer - they are that way stock.
They are not bored out or otherwise any "bigger" than a basic stock non revup lower.

It is most beneficial to a revup motor... however, it has minor gains on a non revup with the right combo of other breather mods.

 

I did the mrev2 and 5/16 on my revup and it made a pretty noticeable difference,mainly on the uptop powerband.Def got a little boost in sound as well,sounded nice.