Cheers Ian,
Interesting, so basically the MREV2 is similar to the lower collector that I already have in my car?
however I have read "When used with on the non-REVUP 350Z engine, the gains when it is installed alone without a spacer are very similar to that of the 5/16" spacer. However, the MREV2 will show a slightly lower peak value, with a slightly higher average value and a slightly higher TQ value. Racers may want to get the spacer AND the MREV2, for improved top-end performance. Overall, MREV2 provides "area under the curve" and is the highest gain plenum mod available. Installs re-using existing factory hardware."
Source:
http://www.thezstore.com/page/TZS/PROD/350z09c/11-3098