fellow honda accord owners. I have a 2004 accord 2.0L i-vitec, matic and I need your advise on how to improve its performance.

1. low range rpm is pathetic specially on 2nd gear
2. there is a half second lag when I press on accelerator
3. ang kupad sa arangkada
4. ang lakas sa gas, Im getting 7.3km/ltr for a 2.0L engine

what I want is a more responsive car, I am willing to modify things under the hood at a max price of 10t siguro. friends tell me change intake and exhaust lang but I worry about its exposure to water elements pag rainy season na, what can you advice a novice like me? thanks.