I changed the coolant sensor and new design plug that goes on it. I've noticed the car is a lot smoother when pulling off, where before it was a little bit jerky.
the plug and sensor have gold plated contacts.
Plug and wire: 93174557
Another one is the air filter. I always put the filter in the bottom of the box first every time. I put it in the top first when putting it back together and you get a lot better seal.
Again I've noticed that the exhaust is a lot quieter and pulled up the hill easier too