I believe Apexi is 2.5" it may be 3.0" .. i'm not a hundred percent sure about that. Don't feel bad about calling them and asking if it's 2.5 or 3" ... if it is 3" then that is a Damn good price, if it is 2.5 it's still a good price. I bought both of my mufflers off of ebay, performance shops and even small shops like Midas(they sell performance mufflers) will RIP you off... I bought a MagnaFlow 2.5" dual tip DTM stlye off of ebay for $60 shipped two years ago for my probe, it had a small ding in it, i took a picture and the guy gave me $15 back for the ding. then had midas put on 2.25" pipe, for like $200.
I loved that Magnaflow, it sounded Great !
I bought a No name brand 3.0 Dual Tip DTM style muffler off of ebay for $70 shipped, and had Midas put 2.5" pipe on my Civic for $170, then had a $15 coupon ...
I don't like this muffler as much, as I stated it's not as loud, but i'm sure that is also due to the fact that the Civic is smaller engine than the Probe. It sounds NICE, but it's not LOUD enough for my taste.
Really it's hard to say if a Name brand muffler will preform A LOT better than a no name, I think, that a free flow muffler, will give you the SAME gains, no matter the make. However, i think a name brand will probably be higher quality and last longer.
One thing MagnaFlow does that I really liked Cosmetically, is they imprint their logo on both muffler tips and both sides of the muffler, so you could see it's a great muffler by looking at it. I have NO clue who made my current muffler, no name, and came in a plain brown box.
N1 is a name brand, but there no where as big as Magnaflow or Apexi, or even the larger Borla's, Nuespeed, Flowmasters... yada yada yada... but basically if it's a really great deal, then go for it.
Also don't forget to haggle for the price on the Pipe Work, I haggled with 4 different shop owners before i had my pipe put on... the first guy told me $250, i haggled down too $215. Then I got $275 out of a guy and didn't even bother with him, Got $275 out of the first midas i went to and haggled him down to $200, but i HAD to pay CASH, and only had credit card. So i didn't get it. later... the second Midas said $180... I had $50 cash and had to put the rest on credit, and i had the $15 coupon... so i came back another day.... later enough for him to forget about me, and said look .... pulled out my money and let him see i had some cash to get him to think i was paying all cash... told him I only had $170 and really wanted to get it done today... he argeed .. then after that i pulled out the coupon and told him I had to put the rest on credit.
But the Apexi isn't a bad deal at all.... but you'd have to bolt it on your self , so get under there and make sure those bolts aren't tooo rusty..