I just got a G35X and I love it so far. I have never moded a car and don't know much about cars. I am looking at moding the intake and filter. I have read mixed reviews about stillen vs z tube and would like any advice about what is better. I am considering going with the Z-tube with K&N filter and motordyne Iso thermal 5/16 spacer. Hopefully you guys can help me with this cuz I can't wait to start moding

Search a bit more. If you can find a z-tube cheap, pick it up. There wont be any performance difference.

Stillen CAI usually comes with z-tube. A good panel filter like Amsoil or K&N plus OEM z-tube is also a good combo, but as 4D says, no real gains. The MD 5/16 will get you a bit, though.

Decent drop-ins will only help performance. K&N here.
5/16th spacer gets a imo

so what is all the hype over z-tubes, if they don't do anything? Some of the blogs I have looked at say z-tubes can give you up to 10hp. Is it only worth buying the spacer and K&N filter. I appreciate all of the help because I have no idea about any of this stuff

btw welcome.

Most people go with the z-tube for the throaty intake sound.

The z-tube transforms the intake sound from quietly powerful, to down right mean. Its definitely worth getting for that sound.. no question

The best mod you can do for the $ is MotorDynes 5/16" spacer ISO. The combination of z-tube and K&N filter will increase the needed air volume in your plenum. The spacer/intake will give you HP you can feel and a very, very cool sound. Stay away from pop chargers unless you're after looks and not performance.
Gary

Gary hit the nail on the head. I didn't feel any difference when I went to a Z-tube, although throttle response did improve a little.

A spacer will help out too. The OEM intake system is pretty good and going aftermarket at that point is mainly for dress-up and noise.

I will say that my G is still VERY quiet with the Z-tube during regular driving with the only difference in noise being at WOT. That's exactly what I wanted, quiet when I'm out with clients and rorty when I wanna have a little fun.

i love my stillen intake with the z tube it produces a very nice sound in my g35x, it was so worth it

BAM! - we're done here!

Something else I forgot to mention... look into the REV-UP airboxes, particularly the back half that connects to the MAF. The final version of the REV-UP airbox has a larger velocity stack than the other airboxes. Might help a little with power, but not much.

I've been thinking about measuring and milling a few of those stacks, but the temptations of boost have been getting to me.

STILLEN airbox/JWT velocity stack/filter - all wrapped with heat tape. That is the best intake.

^^ Just curious, how much different is the JWT velocity stack from the Stillen unit? Pictured just below the filter here:

Best bet is a drop in with the z tube. No drop in performance unlike JWT and Stillen and you still get the aggressive sound above 5k RPM