I am planning to get a cold intake and catback exaust and was wondering if I ran premium gas instead of regular fuel would if damage the engine or make it run better
If you do a lot of freeway driving it will get somewhat better fuel mileage and you might notice some increase in performance after the computer gets done with the relearn of the higher grade fuel, but if you want to really take advantage of the fuel I suggest getting a programmer like a bully dog or something similar. The engine is capable of handeling the fuel so your worries about engine damage is minor as long as everything it up to specs.
Regarding installing cold air and exhaust...I think that just running premium fuel with out a tuner will only result in your wallet getting lighter. It will likely make no difference in MPG or power. Adding a tuner with a premium fuel tune will result in increased Horse Power. Anytime modifications are made to both intake and exhaust the engine tune should be modified with a tuner to get the most out of your modifications.
Complete waste of money your engine can NOT utilize premium fuel to an advantage. Compression ratio is the real factor when considering fuel octane. Regards
Looking for a Used Focus in your area?
CarGurus has 53,618 nationwide Focus listings starting at $1,299.
Search Ford Focus Questions
Ford Focus Experts