Most anything will improve the stock system.

   I can't give an honest opinion on the stock header vs Calmini as I have not had them side by side, but the stock header in this case looks pretty good. I don't know what year your 16v is but on my wife's 92 4dr I went to a 2" front to back from the stockmanifold it wrks great. Noticable difference in scoot and bumped us from 34mpg hi way to 38mpg.
    What year is your 16v and is there an o2 sensor at the CAT?

    Also think of your engine as a system, have you done anything with the air intake side...better air filter, cold air box?
    I combined the exhaust mods with a K&N filter and a damn good tune up to get the above results.
    I measured the gas mileage before and after with 600km round trips (visited my sister).

Thanks for the question...got more info?

Zag

It is a 1997 with the two O2 sensors.  One on the exhaust manifold and one after the cat.

The down pipe and the cat are larger pipes and the cat back are much smaller.

Cwkick

 Ã‚    Unless you want to get into fabbing a front pipe with bigger cat and o2 provision you are probly right in going with only the CAT back.
    But combine it with some breathing mods, like a good low restriction air filter, to get the most out of it.
    If these are the first mods to the engine I think you will be getting pretty good bang for the buck and most likely improving you gas mileage.

Thanks for the question and the info...

Zag

Do you know if a snorkel, will work similar to a cold air intake?

     It all depends on the design...
Watch for these points

- Large diameter, at least what the air intake on the
 engine is.
- Nice smooth bends, no 90 degree square cut corners,
 The fewer the better
- Well sealed, no leaks
- Route away from the radiator, exhaust etc.
- Really good hi flow airfilter with lots of air intake space

If it fits this type of profile it should work similarly.

Thanks for the question

Zag

This was my ideal, a piece of 2 1/2 inch pvs like many of the ppl here have used, a gentel slop from windshield pillar directly to the finder were is goes inside the engin compartment, now
on the motor side use a Highflow shortram style airfilter, inside a chabmer just a little biger then the filter but so that air is not restricted to all the surface of said filter,  and sealed on both sides of filter all the way up tp the roof, were cap the pipe and cut a hole in the front so you don't get hydro lock when it rains
so you have a short ram with a snorkel attachet to it, and a ressonation chamber for the short ram,  should give the intake growel and function for water cross ing  it is connected to the stock intake tube above the exhoust pipe? i dont know how to change that aspect, but i could do heat reflective tape on the  ressonation chamber, that would be closest part to the exhause,  was also thinking of activly cooling the metal portion of the intake system.  some coper heat sinks and some 12V 7,000 rpm fans? " computer fans 40 - 80 MM, should tak out all of the radiated heat from the motor.
any way
Zig  what do ya think

Do you know if a snorkel, will work similar to a cold air intake?

The Safari snorkel probably does give slightly cooler air to the motor but the Track/Kick has no intake heater anyway and the air is taken from outside of the engine bay. I have seen claims that there is a 'ram air' effect but in the case of the safari at least this is nonsense as the head has holes in it to drain the water out. I have never noticed any performance increase with mine, does keep the water out though  .  Personally I wonder if the elbow that connects to the throttle body might be a bit restrictive. With a body lift there is room for a more gradual bend. I wish I had access to a dyno but I haven't found one locally.

Mythose
    Your system sounds good but because of the length it will probly not have much of a cold air effect. Be sure to give the air filter lots of room to breath, i would try to have a couple inches all the way around. As far as fans and heat sink, I would not bother, the amount you would gain is likely out weighed by the power drawn.
    The place you will gain is on the actual air fliter, use a low restriction unit and give it room to breath.
    This would match what Rhinoman was saying, the length of the system, with all the turns is going to zero out any cool air gain.
    This is also different than the pre heat in the manifold. That heats the manifold and TBI to assist atomization (or so goes the theory), the benefit in cold air induction is that engines love cool clean air at the inlet.
    Your comprimise is the lenght you need to have the snorkel operate effectively off road...so I'd do it for the off road benefit and go for the gains on the filter.

    What you need to remember is AIR HATES turning, and really HATES sharp angles. The less you have to turn it and the smoother you can make the turns the more the engine likes it. (generally)

Thanks guys

Zag

wonder if  brought it in through the hood? instead of drilling a hole in the finder cut a slot in the hood up by the heater crowling? and just make it with no shar bends just a gradual twist.

So I need a way to open and close the snorkel, so I can use it off road "as a snorkel" and have a short ram that breaths from out side the fender on road?

but then if it leaks under water you are screwed.

Form follows function...

    I think taking the off road function and the aviable power gains into account your first plan is the better one overall.....a good functional snorkel/safari set up is going to have more gains (with a good aircleaner like I described) overall than hacking up your hood and blocking your vision the other way. (besides I think the snorkel looks cool).
    Every engine application has compromise, here is an example where I would recommend letting the off road benefits win. But you can still get improvements with a good low restriction air filter set up.

Zag

Rhinoman

    A dyno is the most accurate but you can calculate the gains using 1/4 mile or 0-60mph times.
    Moroso makes a slide rule type hp calculator that you can extrapolate from or there are some good computer programs (Dyno Jr for PC's). Now days there are also a bunch of dash mount computerized G meters that give pretty reliable info.

Zag

I am going to go with the  first thought of it and give about 1.5 inches all around the air filter, but I want a round filter that also draws from its sides and front, like a weponr

i used 4" stove pipeing for the intake on the acura, and wraped it in heat repelant tape, gota be carfull in the rain thoe!! its only sucking air about 5" off the road. through a 6" by 3.5" scoop mounted behind were the drivers side fog light should be.  moved the battery and routed a prety straigh 4" round pip up to the stock intake tube with a wepon r air filter in side the tube then sealed it with a cupla pieces of plastic and hose clamps sounds mean,  but the guy buying it wants me to take it off says its not pratical lol  but he has cash , and I told him he could take it off.  but that is not a zuk sorry for the ambiguous post.

Thats sure the right idea for the street...too bad it would be a disaster off road.

Zag