Muffler advice needed (all exhaust gurus, please take a look)

[EEYORE5182@aol.com]

ok, before i start, please do not flame me on muffler choice.. i dont need
that.  what i do need is some advice.
as a new muffler, i have chosen an APEX N1 can, with the removable silencer.
it got here yesterday, and i almost immediately started having some
questions..
to start, i have the new hotshot header, a 2.5" inlet/outlet high flow catco
cat (stock length) and the courtesy midpipe.  i have been running a eurosport
muffler with some crush bent 2.25" piping.  its now rusted out and pretty
much not doing much except making it look like my car has a muffler attached
to it..
the new muffler is said to have a 60mm inlet, and 90 mm outlet.  when i
brought it out of the box, i noticed that the 60 mm inlet goes down to about
2.25" for about a half of an inch before it hits the can.  not TOO big of a
deal.  the inside does open back up to about 2 1/8".
after more looking, i realize that the near the outlet of the muffler, there
is a pipe stuck in the middle of the perforated piping towards the outlet of
the muffler.  essentially, it is a piece of pipe that is about 1 3/4" that
has been flared out to about 2 1/8" and then welded into the inside of the
muffler.  this pipe is about 7 inches or so long.  if you look from the inlet
to the outlet, you see this pipe stuck right in the middle of the flow,
enabling gasses to run beside it and then dead-end to where its spot welded
in!
i know i can bust the spot welds and remove that inner pipe, but its still
going to put the diameter of the piping down to about 2 1/8".  so, my questi
ons are this..
First, due to my very high flowing exhaust (well, to the rear section at
least) would the APEX muffler (after removing the restrictive inlet pipe)
hurt me, or would it add some crucial backpressure to give more torque?
Second, does anyone know about these mufflers or maybe how they where
developed?  if all of this stuff is done for a purpose, then so be it, but to
my monkey brain it looks a little questionable.  i would like to know some
opinions before i modify it, or at worst, send it back.  thanks for the help
as always

Alex
'93 NX2k