Figured I’d write this up and will post pics when I can on my next day off.
This mod is great if you’re on a budget and want to increase your horsepower, mileage and throttle response on a budget and still want to get some decent numbers. The hotshot intake showed dyno numbers of around a 10hp gain, and the other intakes were close… this is probably a 3-5hp gain. I will also post up the socket sizes and tools needed when I get home, for now I’ll post up materials needed.
- You will need a piece of 2.5" muffler tubing the same length as your upper resonator. You will need a muffler shop to flare the end to 2 7/8".
- K&N Drop in replacement filter for the ZX2
- Patience
To install this you will need to unbolt the bolts holding the end of the intake and take it out, you’ll see it has a big giant box on the bottom of it that’s sort of square, this is the lower resonator. Pull that sucker out.
Bolt the intake back up with the lower resonator now removed. Put the K&N drop in filter in. Now you’ll want to undo the clamps for the upper resonator and remove the stock resonator. Put your piece of flared muffler tubing in it’s place (it’s only going to fit one way) and put the clamps back on.
You should now have no upper resonator, a K&N drop in and no lower resonator. You’ve now got more air flow coming through it, better air flow from the filter and a smoother flow through the top part of your intake.
This is a good mod for the people that want to do something with the stock intake without the pain of redoing your entire intake setup. The total cost is around $50 after the filter and muffler tubing (I had a muffler shop do mine, cost me $10 for the pipe, $40 for the filter). It’ll be a bit more throaty at higher revs and sounds better than using PVC pipe like some people do use, not to mention muffler tubing won’t melt or mis-shape itself over time 
and you aren’t opening it too much, just about right, and any increase is a good increase.
Pics, tools and socket sizes to come… i’ll make it detailed.
