Last night after installing the plugs, I took it out for a ride. The time was around 12 am. First my brother drove the car and he said that the engine sound is reduced (but he was asking how can sound reduced by just changing the plugs :)). he tried to rev it hard and the response better than before.
On way back I drove the car. On an empty and a little bit while road, I tried to calculate 0-100 time 
(it was my first time doing anything like that). On the launch, the tires span for some time a the car lost a little bit traction (I don't whether it was because of torque or something). In the first gear, I was a little bit late to shift the gear and RPM went a little bit beyond red line. When I shifted to 2nd gear, we felt a great deal of push forward when clutch was released :). It was fun doing that provided that we ensured all the possible safety measures.
On high revs, engine was stable and also sound was less than before.
