So I decided to go with a 350Z

[EJ25RUN]

You're right, HR started in 07, but I think the LED taillights came in 06. Not sure about the headlights. Originally, I thought you were gonna say something about the rev-up vs. non rev-up engines...

explain...

[DieselNuts]

explain...

Here you go

Q: What is the difference between the REV-UP (300hp) and the NON-REVUP (287hp) Motor? Which one do I have?
A: Rev-up Motor has higher peak HP, lower peak torque, and a higher redline (7000RPM)
Non-rev-up Motor has lower peak HP, higher peak torque, and a lower redline (6600RPM)

Rev-Up Motor has variable Intake and Exhaust timing.
Non-Revup Motor ONLY has variable Intake timing.

You can tell which one you have by looking at your redline on your tachometer.

Q: What is a MREV, and MREV2? Which one do I need for my rev-up (300hp) or non-rev-up 287hp motor?

For 2003 - 2006 350Z's / G35's, Nissan has designed two different types of lower collector:

REV-UP lower collector from the 300hp motor = shorter runners which are tuned for lower peak torque, but higher peak horsepower.
NON-REV-UP lower collector from the 287hp motor = longer runners which are tuned for higher peak torque, but lower peak horsepower.

MREV = same exact thing as the non-rev-up lower collector, but Motordyne Enginering has given it a name.
MREV2 = Using the MREV as a starting material, this is a CUSTOM lower plenum that is sold by Motordyne Engineering. It has been precisely machined to remove aluminum from critical locations on the MREV. In other words, it is like a much improved version of the MREV which reduces restriction and improves HP / TQ.

If you have a non-revup motor (6600RPM redline), your best bang for your buck is to get the 5/16" spacer. The 5/16" spacer makes the most HP for the money. OR, you may choose to get the MREV2. By replacing your stock lower collector (MREV) with this better flowing version, you will make better "area under the curve" on the dyno in terms of HP gain. My opinion is that you should choose one or the other -- either MREV2 OR 5/16" spacer. If you get both, the HP gain will exhibit "diminishing returns", meaning you will spend a lot more money to make not much extra HP. So, usually the recommended option for the non-revup guys is to get the 5/16" spacer.

If you are a rev-up owner (7000RPM redline), you will basically only benefit from getting BOTH a 5/16" spacer and the MREV2. If you get the MREV2 only, your mid-range torque will increase but your maximum HP will drop off severely. If you only get the 5/16" spacer, you will not see a benefit. Several dynos have proven that for the rev-up motor, you basically need both the spacer and the MREV2, which will make a lot of midrange torque, without sacrificing too much peak HP.