i posted this to the main list, but i was hoping that people here would take a look. this is what my post said:

"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 questions 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"

I would just get a true 2.5 inch that doesn't neck down or have any obstructions. My mufflers looked like they did neck down but that is not true. The first 2 inch on each end are oversized so that you can just slide a 2.5 inch pipe in and then it is a consitant size front to back. Just so you know this is common with mufflers. I thought mine necked down but it was only this oversized part. I was seeing.

BTW are you in Hampton. If so see you friday.

are you sure its an actual Apexi N1, or is it a generic?

Originally posted by NXTremeSE-R
a 2.5" inlet/outlet high flow catco cat (stock length) and the courtesy midpipe.
Can you confirm the Courtesy unit is 2.5 inches or 60mm from end to end.

shoes - its 60mm

slipper- its real. if its a knock off, someone has gone through a lot of work. has the metal A'PEXi tag welded on the can, has the engravings on the tip, and came in an A'PEXi box.

well, i successfully busted out the inner pipe tonight. the inner diameter of the pipe inside the muffler was about 1.6". it took a while to bust the metal away from the spot welds...but its done..and i really didnt mess it up. need to do a little more work to make it pretty. but all and all, should be alright. the smallest the muffler goes to is 2"+ for a couple of inches. mike K says that a 2" exhaust is good for our cars, and since the rest of my exhaust is high flow, i should be cool..keep your fingers crossed..