Since I just saw this in a couple topics, I thought I'd make a post about it....
When you install an intake, you take out the resonator in the fenderwell (a device that honda put in to quiet down the nice rumbling sound you hear from engine noise reverberating back out the intake manifold and intake).....that resonator has a butterfly valve in it that does god-knows-what, but there is a vacuum line from that butterfly valve to a black box right over the tranny mount......from that black box, there are either one or 2 vacuum lines (depending if you're OBD1 or OBD2) that go to a single line that attaches to the intake manifold.....
It is perfectly fine to remove all of that crap after putting in an intake....remove the black box (unplug the wire clip going to it and just leave it hanging) and all the lines attached to it. Make sure to put a vacuum cap on the nipple on the intake manifold that the old vacuum line went to (actually, it would be better to put a boost gauge on there heheheh)
Brian

 

As I said in the other post:

That "little black vacuum hose" does nothing important once the resonator is gone. I've pulled the resonators on 5 4th gen Prelude's, not one of which idled any different afterward.

 

I know, this post wasn't in reference to your post And you mean little black box, not hose (stock vacuum hose is black, but I'm saying you can physically unplug and remove that box - a lot of people don't know they can do that or are afraid they're gonna mess something up), and if you don't plug that nipple on the intake manifold from the hose to the black box it will affect your idle, it'll be about 1200 rpm's higher......
Brian

 

never affected the idle on any car I've ever seen... *shrug*
But I'm a fourth gen freak.

 

I have never plugged that vaccum line. Its just dangling around still. So I don't think you "need" to plug it, I think it really makes no difference.

 

I'm not talking about plugging the vacuum line (like with a golf tee like everyone suggests), that line should be removed anyways.....I'm talking about plugging the nipple on the intake manifold that the line from the black box used to attach to......you shouldn't have that line dangling around, you should take it out because it's useless.....that was the whole point of this post, was to let people know you can remove all of that stuff instead of leaving it dangling around.....sheesh
Brian

 

I take everything out.... then put back the bare minimum after it quits working.