Had to change brakes, when I tuned the engine.
I was involved in an car accident, and my Escort was crunched in the front.
After I changed the air filters (K&N) and chipped the car, it really started to be fast. I don't know how many HP I have got now, but the car is faster than before.
For best performance use 195/50R15 Dunlop R9000 tires.
How much does it cost to chip the car, can all Si's be chipped? I just bought one and think it's OK, but it could do with a bit more get up and go.