so far 3 well known friends stated that they felt big improvment in the car's performance after the installation of the spark plugs so i had to get a set for me.
after the installation (they replased Denso U groved spark plugs) i felt nothing has changed... nothing.

i have asked the guys again and they confirmed that the spark plugs made huge difference to the car performance, i let one of them to test drive my car and after the test drive he said: "the car pulls a bit slower than mine at low RPM but at high RPM it is better than mine".
the dude got a brand new 05' Lanos with less than 5,000 Kms on it and my car is a '99 Lanos with 62,500 Kms on it. it didn't make since to be that he felt such improvment and i didn't yet he was satisfied with the test drive.
i think the reason behind that feedback was the fact that i swapped the Denso with the BOSCH spark plugs while the other guys swapped the OEM Champion spark plugs which are not that good to start with... so practically the big bang they felt was due to the bad spark plugs they started with, i was already running on good spark plugs so i felt no difference.
as for the low and high performace differences... i think mine pulls slower at low RPM due to it is a 6 1/2 years old car with 62,500Kms on it and it got a 11 Kg jack and 30 Kg tool bag in the trunk, the high RPM superiority i got was due to removed resonator and CAT... i guess

what do you think guys?? i know the super 4 spark plugs doesn't add performance (its more about durability) but what about the "more power" feedback from the other fellow woo owners? and what about the performace fifference at low and high RPM compared to a brand new woo??... any ideas?
MMamdouh