[QUOTE=kailep]I have read somewhere that the Ztube has no resonators on it where the stock G35 intake tube has two resonators on them. So the Ztube should be less restrictive.

 

The plastic screws (they're actually a type of rivet...they're not threaded) are the exact same ones that are used throughout the car (but w/ a different head on them).....not sure if you know what I'm talking about, but if you do, you'll know how they work. There are only two of them that get removed....the top of them (visible part) is almost flush w/ the top of the box. No need to peel open the filter box at all. You need something long enough to give you leverage and something that is wide enough so you'll be able to touch the end of the rivet w/ some margin of error (since you can't see it, but you can feel it if yout stick your hand inside the box). I used med. size screwdriver, stuck the handle portion of it inside the box (underneath the rivet). Simply use some leverage & pull/push up on the rivet & use your 2nd hand to place over the top of the rivet outside of the box, so it doesn't go flying into your engine bay . Simple as that.

Since my last post, I've experimented a bit more w/ driving w/ the duct removed & I am a lot more impressed now that I've driven it a bit more. I got on the gas a lot more and WOW...the freaking thing roars (but only when you're up between 3K-5,5000). Almost sounds too loud (not sure how safe this is for the engine)...I'm guessing it's fine, as all that's happening is more air is flowing thru the engine. The most impressive scenario is when you're in automatic mode and get on it.....when the car shifts from 1st gear into 2nd....and the RPM need drops.....right when it's @ 5K in 2nd gear, I find it the most impressive sounding! Not sure if I'll be keeping this like this for long, since I've notice my mileage is FAR worse now (since I've been "lead footing" it a lot more than usual). ENJOY & let me know your impressions!

 

[QUOTE=jimmykce1]That's exactly it...you really don't see how big/obtrusive the stock tube resonators are until you remove it! One of them is recessed down towards the ground, and is probably 6"-8" deep! The 2nd one is that boxy looking thing that sits on top, that looks like it has a top on it that you can pry off. My guess is these resonators act as "mufflers" which reduce the noise or "resonating". Not sure how some of the members above are not witnessing any more intake noise....my guess is they may not be getting on the throttle enough? You really need to get on it and get the rpm's up from 3K-6K to hear it. I was very happy when I did the mod w/ the K&N (my 1st two mods).

 

As was said earlier, if you're looking for a little more sound try removing the "power duct" cover located on the airbox itself. It's just a 4" piece of plastic and foam rubber, but that little guy makes a big diff in sound. On my car ('05AT) It basically doubled the sound of the ztube.

Just take the handle of a hammer, or other long tool, and stick it in the airbox then leverage pressue up on the bottom of the plastic tabs that hold it on. Took maybe 20secs to take it off.

 

Gotcha. I'll give it a try later. Thanks...

 

Ok, I removed the power duct just now and took it out for a quick spin. Only drove a couple blocks...will try it again later on. It was a little louder without the power duct. I went to around 4,000 - 4,500rpm and WOT and didn't noticed the "loud sound" that you guys were mentioning here. Will update it when I get out later.

As for the screws. It was just a pain. Either I am not using the right tools, not doing it correctly or whatever, I wasn't able to pop the plastic screws from inside out. I ended up having to flip it from the top with a screw driver. Left some marks on the power duct under the plastic screws but gets cover up by it when I put it back so it's alrite. Plus I'll probably get the Stillen cai and replace it anyway.

When you stick the end of a screw driver in, how you pop it up? I mean my hands are not that big but didn't seem to work for me.

 

that's really weird - try driving in 2nd gear about 35KPH(KPH, don't know what MPH is, heh) then downshift into 1st and give it some gas - in the coupe it sounds like you've got a stroked out engine or something with a hella lot of displacement - there's a huge impact in exhaust note.

although i can't explain it, it think it has to do with the exhaust setup (probably the mid-resonator).........sedans don't seem to notice anything major from it, coupes seem to notice a bit more *shrug*

 

Yeah, I just got my K&N and Z-Tube installed this weekend and wow, after removing the power duct, it really does seem to add a little umph to the sound while driving in the 3k-5k rpm range . It was quite fun hearing the thing roar, but I dont' think I'm going to keep it off because I noticed the drop in mileage as well like someone pointed out since I've been flooring it a lot more... THe K&N and Z-Tube mod is good enough for me. However, I've read a lot of threads/posts on the Z-Tube and many have complained that the Z-Tube actually doesn't do much and that the stock tube is better with the K&N. What's your opinion on all this? Thanks for all the feedback.

 

Ok back from more driving. The "power duct off" does give it a little more roar but not by that much. I guess it's a good imitation I can get before I go ahead and order the Stillen CAI. Hehe...maybe I'll just put the power duct back on for now...

 

With the sedan, no change in exhaust note...just the induction/Z-tube noise is deepened & amplified.

EicarG35 - I really don't see how the stock tube will work better w/ the K&N. The tubes are the same exact size, shape, etc....the only difference is the resonators. I thought the Z-tube minimally increases HP (1 or 2), but definitely doesn't decrease performance (mileage maybe).

 

I still maintain that the z-tube is the biggest scam ever perpetrated on g35 owners. Save your money. I regret getting my z-tube, it does absolutely nothing.

 

Why doesn't somebody with a "Z-Tube" put this controversy to rest
and dyno their car WITH and then WITHOUT the Z-Tube.

Do at least 2 runs with the tube then, to be fair, remove
the tube, put the stock one back on, let the car cool
for a bit and do at least 2 more runs (on the same dyno on
the same day) and give everybody the results.

If this Z-Tube really does absolutely nothing, the couple
people who do this dyno test will be MUCH appreciated
and save other people A LOT of money in NOT purchasing
this "mod" if they are under the false perception it
actually does boost power.

 

This dyno tetst you want has been done - in fact searching may reveal that it was done this month! And no one should ever put a Z tube on their car, for power anyway. The hundreds that have that I ama aware of did it for sound alone. If you want sound and don't want to spend the $75 for a new tube, just stick on muffler patch on the inside of the G tube and cover up the holes to the resonators. Works like a charm

 

Does your airbox close back snug after the K&N has been installed or does it seem as if the box doesn't close perfectly? After I intsalled my K&N, I couldn't remember if the airbox was closed snug before with the stock air filter, but now, even though it closes and all, the two pieces of the box doesn't seem to fit perfectly together? There seems to be creases on all sides of the stock air filter so I was thinking maybe it was just supposed to be squeezed in because with the K&N, right now it doesn't have perfect fitment even though it's closed with all 4 clips. Thanks for the feedback!

 

Any thoughts guys?