I had a custom 2.5" cat-back (well, straight pipe back) made today. Since I sold me stock 2k2 muffler the one I've had for a while got welded to the new cat-back. Its a dual straight thru muffler as pictured below. With the cat-back on, there is a little more noise than I'd like, so to fix that temporarily I've blocked off one of the outlets from the muffler. Now getting to my question, the outlet that is open is around 1.5 or 2 inches in diameter, how much, if any, power is gonna be lost by only having that one outlet open? I figure since the stock muffler keeps just one outlet open for normal driving, my setup will be decent for that, but under WOT, i'm just curious if any of you know something about flow rates and how being pushed thru that small opening at the very end of my exhaust setup will counteract (or do nothing to) any gains I recieved by getting the 2.5 inch cat-back setup. OK thanks for any input, and below is the pic of the muffler prior to blocking off 1 outlet

 

how much did the set-up cost you? Did you go to a local muffler shop?

 

You might notice a difference in top end pull (like 4000-redline) but it probably wouldnt be too bad. Just mess around with it.

 

The setup, from straight pipe back to the muffler inlet with 2.5 inch piping and a large resonator cost $165 installed. Good deal if ya ask me. The guy that did it was in a little hole-in-the-wall shop in Worcester, not a good location but he knew what he was doin. After driving around today with the one outlet blocked off, I'm lovin it. Sound is perfect (not that I know what it sounds like from outside the car, but inside is good). Not too loud, but I still want to find a stock 2k2 muffler to toss back on in prep for headers. But anyways, if anyone is int he CT/MA/NH region and wants a pretty good cat-back for cheap, i'll get ya the info on this guy. I'm the second Maxima he's done, me and the other guy are both pleased.

 

um... i think what you need is good.. you created back pressure...
you migth want to put on a little butterfly opening that opens under wot

 

Just buy any $50 "turbo muffler", check Summit.

Especially, since you're concerned now about the sound level and you intend on getting headers.