1999 Honda Civic Si Modified Specifications Engine: 1.6 L DOHC VTEC This engine runs best with fully synthetic oil. We have made extensive research in order to find out the best quality synthetic oils on the market. Don't forget that the oil filter is as important as the motor oil. Discover a…

Looking to improve your ride? Upgrade your Honda Civic SI Coupe with Street Aero's NEW sleek and stylish rear diffuser! Designed specifically for your car and bumper, our Rear Diffuser is easy to install and instantly enhances your build by giving it a sporty, aggressive look. Our aftermarket car parts are the best choice for enthusiasts who demand the highest quality customizations for their vehicles, but at the lowest cost.