when i did mine i just used a sharp razor blade and cut them flush.  then i took apart the reed cage and just bolted the flange to the intake boot, then ported the boot to match the opening of the flange.  just be carefull porting the boot or you'll go through the side.  dremel tool with a sanding drum works good, just be carefull.  you can see the one in the pictures has been ported.  personally wouldn't use a hack saw, you could bugger up the boot flange or the plastic reed flange.