There is no specific increase in the performance......If your cables are weak and plugs are new even then it can effect the performance of the car.......I recomend you to put 1tip plugs in all japanese cars they are only good for German cars as their engines have 4 tips plugs in stock EG BMW...........
I have them in my civic i bought them for DHS230.00 from Bosch dealers i felt good but that was just because they were new and all new plugs have a better effect on the performance.