Alright, so I am totally new to g35 terminology so I have been reading a lot of past threads to try to figure out some things.

- Z TUBE - the intake tube from a 350z that G35 owners put on their Gs to avoid sound baffles and have less air restriction. But they don't really add any horsepower and just sound cool. (I'll prob buy one, lol.)

- SPACER - Basically a thicker gasket?? Reduces heat soak in the engine block and will gain 10-15 hp for a G.
**Quick question - Will this effect the heater in anyway? I had something like this on my 2000 Honda Prelude, and my car had the hardest warming up on cold days. The engine temp gauge actually dropped when I sat at a light, and cold air would start blowing form the vents.

- REV UP ENGINE - I haven't totally figured this one out, but I'm thinking these are the G35s that got the update in HP from 280 hp to 298 hp? And this came in 2006+ G35s

POP CHARGER - From what I can put together, this is a cone air filter?

Since I have a 2003 G, I'm assuming it is not a REV-UP engine. I also saw some owners are buying 2006+ air boxes.

I am thinking about doing the ZTUBE, 2006 airbox, and spacer. I want to look as stock as possible. Then I plan to get 19" rays and lower the G. I will be pretty much done at that point.

Are my assumptions on all of the above correct? Thanks for reading.

-Grateful Noob.

yes you are correct on everything except:

The spacers will not affect your heater.

The rev up is on 05 models and up.

and the pop charger sounds better than most other cone filters, and also comes with a heat shield. you wont be able to use the popcharger/heat shield if you get the 06 air box.

You won't get 10-15 HP from a plenum spacer. More realistically you may gain about 3 or 4 WHP or possibly 5-6 crank HP.

I thought I remember reading that the Z-tube actually did give you a slight HP gain.. but it definitely makes your exhaust sound cooler when you rev it up having that in there.


Since you have an '03(I have an '04, so it's basically the same car as you)... I recommend getting a Z-Tube, a 3/8" plenum spacer(assuming Motordyne still makes them in that size), and a drop-in Amsoil EA Nanofiber air filter. The Z-Tube and Amsoil air filter will cost you about $80 combined. I forget how much i payed for the motordyne spacer.

So if I get a plenum spacer, ztube, 06 airbox, and AMSOIL drop in filter, could i realistically say i gained 10 whp?

I don't want to get into a cycle i had with my honda prelude where i spent $1000 for 3 hp. hahaha.

I also want another reason to justify spending $500 besides a louder car.

I'd just forget about the '06 airbox... the factory one is pretty good as is and sucks in cool air with the way the front end of the car is designed to funnel fresh air into the intake when you're moving.

I got 9whp from my MD 5/16 spacer. 2-3whp from ztube + jwt.

which size is best for spacers? and from what i hear, motordyne spacers are the best?


- fellow noob.

Anything more than 3/8" and you'll have to remove your engine cover, since it won't fit on with a spacer bigger than that on there. Even with the 3/8" spacer, it's a tight fit... but generally speaking, the higher the spacer, the more benefit... only you get diminishing returns the larger you go beyond 1/4"... so it's not really worth it to go super huge.

If you don't care about not having an engine cover, get the 1/2"... if you still want the cover and the stock-looking engine bay, then get the 3/8".

3/8 spacer has shown good gains throughout the entire powerband.

1/2 usually shows a bit of sacrifice on the low end for higher peak numbers.

isnt the recommend size everybody always saying is 5/16???

From what I hear you might not want to discount the '06 airbox. I believe it comes in '05 coupes as well since I have one. Basically it adds a velocity stack to increase flow. The design was changed for a reason.

the REV-UP airboxes only come on 05+ 6MT G and autos do not get it even 05+

So if I have an 03 AT, will the 05+ REV-UP airbox fit?

Oh the joys of having an auto...ha.

yes it will fit the 03 airbox with no mod needed

is there z-tubes for 08 sedans?