I think its because your enigne is such a small displacement and naturally aspirated, we dont have the naturally aspirated 1.8L engine in Canada, ours are supercharged, so they are pretty responsive.
An intake may make your care slightly more responsive, but I cant completely say it will, it for sure will not give you any HP gains, but maybe a slightly more responsive feel. its not a super expensive mod to do, so it may be worth while, plus it will sound nice too!
The only real way to open up that engine is to either turbo or supercharge it. but that will cost some serious $$$$$!!
Does your engine have a rough feel at idle?, any check enigne light on?
what grade of gas do you use in it?
try adjusting the throttle cable a bit tighter, feel the cable for slack, if there is a lot of slack it takes more pedal travel to actuate the throttle, you can adjust tension on it, by turning the plastic nut on the cable, but dont tighten it too much as the idle rpm will increase on you, just turn the nut enough to take out the slack.
hope this helps.