You will see a couple of HP's but nothing dramatic but it's noticable.
It will also make your car louder and you will hear a sucking sound coming from your engine compartment.
With any of the chips, you will get maybe a pony or two for the stock program.
If you have an auto, it also changes your shift points.
Also, you can have the rev limiter and the 108mph speed limiter removed. Just make sure to ask them to remove them when you purchase.
Not sure if anyone on this forum as used the ZEX kit on an auto tranny. I know a few on this forum do have the ZEX wet kit on their Focus with manual tranny.
The best thing about the chip for those of us with the ATX is the shifting seems to firm up and it raises the speed limiter. Who cares about the HP increase. As for a mod for your intake, look around here for a used one. Most of the people here won't sell there junk on here. Another way to go is with the MAC Short Ram. It is a rather nice and cheap starter intake.