For a RM60k++, it worthit. There's some vid on the 1st page. Check it out.. 

hmmm...for me i dun like modifying exhaust pipe.stick to original..so will installing air filter helps da pickup?

Changing air filter does help with pickup, but for the amount of money spent, extractor (header) will give more improvement (rdon't forget to remove cat-con also  ). But if change extractor and de-cat, you will need to change the muffler (optional though) as the sound is less bassy, like empty can when accellarating hard .

Just curious about the Iridium plugs.. how long it lasts? is it worth to buy in term of value vs. the normal plug? do we need to re-tune the ECU to suit the plug?

Investing in a better plug will improve performance, but for me, the amount gain is not worth the money spent. 

Unless there is no other mod can be done.