I am wanting to do my first performance upgrade. I was ready to buy the Injen CAI because I hadn't read anything about the Motordyne or plenum upgrades. I am now considering doing the Motordyne upgrade instead of the CAI.

Which is better if I can only do one? In the future I may do both but want to know what is the best to do first. Please help. Thanks GF.

 

There is a group buy going on for the MD spacer and iso thermal kit you might want to check that out.

 

I don't have any experience with the CAI, but the Motordyne Plenum Spacer is a very good mod. It makes nice HP results on my "butt dyno" and dyno charts. One of the best mod "bangs for the buck" You can always do a search on the Injen CAI. I've read pros and cons on performance and actual HP gain.

 

What year G do you have? The Motordyne Plenum spacer adds a dyno proven 10 HP to the pre-2005 G35s. The 2005 G35 appears to gain few to none HP.
I consider the 3/8" spacer I bought to be my best bang for the buck.

 

If you do a search, you'll find that CAIs for the G35 have a very varied response. Many that have done the CAIs have gone back to the stock airbox (with Z-Tube, and usually with a K&N panel filter) as there is little gain to be had wiht the CAI, especially at the low end. Many have found some losses there, but report some gain at high rpm. Of course there is the dreaded hydro-lock controversy, and if nothing else, they are a pain to clean.

With the plenum mods, there is little debate about the benefits, other than for the '05 6MT.

 

Mine is an 04 Coupe A/T. I am now heavily leaning toward the spacer then. I want to keep the stock engine cover so I guess I better stick with the 5/16 correct?

 

I vote spacer especially if you live in a warmer climate. The CAI may or may not produce any gains and may produce TQ losses. The stock box does a better job of insulating against hot air in the engine compartment in warm/hot temperatures.

The spacer is a proven HP/TQ addition. It is the most significant power addition you can do to the G under $250.

5/16" will let you fit the cover.

 

There is a Group Buy going on right now on My350z.com on the Motordyne Plenum spacers and the Iso Thermal plenum gasket with the Coolant Control Valve. I am adding the Iso Thermal Plenum gasket and the Coolant Control Valve to my mods! Visit Motordyne Engineering web site for all the particulars.....

 

I have a coupe with INJEN CAI.
I don't feel more power but I don't care.
The sound that it makes and the way that it makes my exhaust and engine sound are incredible.
I actually just ordered the Motordyne plenum and thermal kit throught he group buy and should be getting it in about a week.
I think it'll be a great combo.

 

Do them both, I have both of them the power curve is awsome. I dynoed with just the spacer and the intake at 239Hp and 235Tq.

 

I have a 2004 G35 Coupe 6MT and through Tony's recommendation from Motordyne, I got the #6 Plenum kit, the 5/16 spacer with CCV. I ordered it Friday morning and received it Saturday morning. Wow! Talking about fast reliable service.

The installation took me about 2 hours. I was carefully reading the enclosed instruction making sure not to skip any steps. Anyway, I can really feel the added HP gain. I have an Injen CAI and Stillen Dual Catback Exhaust and I am amazed by the added HP. Though I noticed that the sound is a little louder than with stock plenum which is okay by me. For me the louder the better. Sorry no dyno chart. I should have done a before and after installation but oh well.

Overall, I am pleased with the mod.

 

get a K&N drop in, z-tube & the spacer.
I had JWT popcharger, a chunk of change for iffy results.
spacer & thermal gasket will give better performance returns
my 2 cents

 

I agree with the above....I have the K&N,Z Tube and 3/8" MD spacer and will be adding the thermal kit upgrade this weekend.