I' ve done some reading on AIS removal by Kev (thanks Jmo) and the points I concentrate on are:
1.This mod is not recommended for STD exhausts.
2. On any case, removing the AIS will result in less clean emissions and problems with the catalytic converter.

So I guess the only proper way to get rid of the popping sound is by improving the combustion process. Maybe by introducing a second spark plug.