All it is is a little piece of conical wire mesh ment to keep a bird or some large forign object from entering your engine should something find its way into your intake tube. the DPFI system is basically tuned around that stock intake pipe and there is really no benefit to modding the intake or taking that screen off.. get a free flowing exhaust and mabye crank up your ignition timing a little and give it a proper tuneup with stock parts and new air and gas filter.. . change the oil mabye oven go to a full synthetic or synthetic blend.. . . and thats about all you can do for the little guy. . .
Your best bet is to do the MPFI swap... youll see the most power increase.. . . Couple with with the si camshaft.. and your power level will be up there pretty close to the si engine..
If you plan to do an engine swap in the future you will need to have the MPFI swap done anyway.. .
youl have to wait for an auto crosser here to answer the class rule.. . . not sure.. the mpfi swap you are just have to keep looking through the classifieds on here and ebay and such and try to gather up all of the parts that you will need. .
i had one for sale a while ago. i picked it up for $180 CDN, including the SI harness, throttle body, ecu, resistor box, fuel rail and injectors. when someone wrote my car off, i pulled that out and sold it for $150 without the harness. if you can find one at a wrecker's and they arent going to core the engine, then you are lucky. dont offer them any more than what i told you.
easier to find this upgrade on forums. it took me about a month of searching to find someone who wasnt a pirate, and who could tell me details about the car it was coming out of (like mileage)
the wiring itself isnt so bad either. there are a few good write-ups around. i will post the links later today when im back at home.