whats up man...basically any modification dealing with better flow is going to give you more power, some more noticable then others obviously.

In terms of CAI (Cold Air Intakes) they are much better then stock restrictive intakes plus the colder the air the better.  Chips are great but you really dont need one at this point in time..I would wait until more in depth modification...for the time being stick with the CAI or even a short ram intake...you can go to places like NOPI Online or Auto Dynamic if you dont trust ebay.  Pick up a copy of turbo magazine or any other similar tuning magazine and youll see tons of ads for places...be sure to check to see if an eclipse is being featured as well..u can get more ideas that way after your intake move along to the exhaust a more free flowing cat and a less restrictive muffler and you'll have a more sporty engine tone.  hope this helps

Alright first of all if you really want to get some in depth information on the 3G eclipse go visit and join www.neweclipse.org I have been a part of those forums since August 01' and they have helped many times, and for the most part everyone is friendly.

Now as for your intake, I have one (I have an 00' GT) but it is a relatively cheap thing to do that actually does quite a bit for the price..."bang for the buck". Plus the stock air box sucks. *no pun intended*

About the chip...plain and simple: Don't buy one. The reason being is because our cars DO NOT have chips. Everything is controled via ECU (Electronic Control Unit). Now that is not to say that you cannot do anything for the car in that particular aspect. In older cars and some domestics and a few imports today they have chips that you replace based on you modifications and so on. Our cars what you would have to do is find someone to re-flash your ECU. Which means they re-program it to suit whatever type of driving you would be doing and what you have done to your car. Now since you just bought the car and don't have anyting one, I would not even think about that yet. That is something that you would think about way in the future. The stock ECU is actually quite capable of handling more than you might think.

Spend your money on some headers, exhaust, AFR (Air-Fuel Regulator) *if you get headers, they tend to yield another 15 or so if you tune them with an AFR*. Or even a turbo kit or supercharger kit. There is one supercharger kit that has done wonders for the 3G and the company and people are all very easy to talk to and keep in touch with. There are a few options for turbos, but if you visit the above site you will find more information than you know what to do with.

Hope this all helped, I know it was a little lengthy.