Providing your ignition system is all up to scratch, then you can run a larger plug gap, which give a better combustion, and this may see an improvement in both economy and power. However, on a 130bhp car, don't expect to feel much other than a bit of a "cleaner" response. Completely pointless if your leads / plugs / dizzy is 50 years old and done a 1,000,000 miles .