Note:  This guide applies to certain aftermarket baffles.  These basic techniques
may also work on some stock baffles in OEM pipes and baffles in after-market
pipes.  You'll need to examine your pipes to be sure.  Modifying baffles as shown
here should not require any adjustment to the jetting of the carb other than maybe
adjusting the idle speed if it speeds up a bit as the engine breathes better.

Baffle Mod Instructions - Tune Your Baffles For The Sound You Want

Many baffles come with several tabs bent inward toward the center of the pipe.
This, along with the slight drop in inside pipe diameter, is what makes
the baffle a baffle.  Essentially it is a silencer.  The tabs and drop in inner
exhaust pipe diameter cause a restriction (back pressure) that dampens
the noise produced by the long hollow drag pipe.
See pictures baffle1.jpg & baffle2.jpg.

baffle1.jpg

baffle2.jpg

You can tune the sound produced by these baffles by bending the tabs out to
change the amount of restriction they produce.  Be careful doing this.  Only
bend a few tabs at a time till you get your desired sound.
See pictures baffle3.jpg & baffle4.jpg.

baffle3.jpg

baffle4.jpg

To bend the tabs out use a flat blade screwdriver and hammer.  Stick the
screwdriver in the hole opposite the tab you wish to bend.  Stick the
screwdriver in the right side to bend the left side tab out.  Bend the tab
as far out as you can then place the baffle on  a couple pieces of wood
and use the hammer with the screwdriver to pound the tab out.  Use the
screwdriver to bend the tab back out as far as possible then use the
hammer to pound the tab flat against the side of the baffle.  Again place
the baffle on the pieces of wood to pound the tab flat.  Pounding on the
wood will keep the baffle from bending out-of-round, which would make
it not fit into the exhaust pipe.
See pictures baffle5.jpg, baffle6.jpg & baffle4.jpg.

baffle5.jpg

baffle6.jpg

Drill a 1/4 inch hole in the back side of the exhaust pipe just above the
lowest point on the pipe, approximately the 7 o'clock position,  for the
mounting bolt.  Drill the hole about 5 inches from the end of the pipe.
That will place the baffle far enough inside the pipe that it will not be
visible yet not so far that you won't be able to reach to install and
tighten the bolt.
See pictures baffle7.jpg & baffle8.jpg.

baffle7.jpg

baffle8.jpg