I heard that there are two kinds, short tube and long tube (talking about aftermarket ones).
What are the main differences between them?
And which is the best intake?

 

You are going to find as many opinions about intakes as there are actual intakes.

A good, non-obtrusive, basically invisible aftermarket intake is the Comptech Icebox. On the dyno, it seems to provide more HP than the AEM CAI, and the Icebox is basically invisible under the hood. It has a black plastic box that's very much like the OEM unit, and people won't even notice it at first.

If you are after the absolute best HP you can possibly get out of an intake, don't care about noise and/or intend to extensively modify your engine, then there is no substitute for the filter on a stick. AEM and many other people make one of these.

They're basically all the same, and will get the maximum HP out of a modified motor. You want to make sure they come with a smooth tube connecting the filter to the throttle body, and you want to make sure it tapers appropriately to the throttle body.

Accepting all that, however, they're basically the same.

They are noisy!

On a street driven ITR with just your basic modifications (IHE), then I'd recommend the Comptech Icebox.

 

Ive had both the AEM CAI and now the Icebox, and ive kept on to the icebox because it has much better throttle response, makes pretty much the same power as the aem, is much quieter and you dont have to worry about having the filter so close to the ground (hydrolock if you run over a large puddle etc..)

 

I guess the short tube is a tube that brings the fiilter to behind your headlight and a long tube brings the filter to behind the bumper?
Are there significant differences between the noise level?

 

Well, with a short ram intake as it's been dubbed in all the car magazines, it's a good deal louder at lower rpms, as it's basically closer to the car, in fact, probably louder all togather, Though I will say, that the CAI, which is the long tube design you mentioned does sounds different completely. I'd say it's not really a matter of louder or softer, as anything you run with an open filter will be loud as hell, it's more just a matter of which makes more power, that being almost any of the cold air intakes.

As George said, the ice box is a nice piece, is very quiet, and hardly noticable. I had the Injen CAI before I bought the ice box, and am very glad that I switched. It's less than half the volume, and I dont know about throttle response, but it does perform as well if not better in most applications. Relistically, on the dyno, at least on my car they made comparable power, basically just making small amounts of power in different places, but as far as sound quality and maintenence ease goes, the ice box is definitely the way to go hands down. If you plan to do a turbo or supercharger setup, you may want to consider an open filter, but for all motor, I run a 2 liter with Toda Spec-C cams and a 70mm tb, and as far as I can tell, other than quieting it down, the ice box didn't have any adverse affects over a cold air style intake.

Good luck,
Aj

 

This sums it all up for me. I really like my Icebox.