[QUOTE=DaveB;6101659]The muffler looks great. Are you kidding about opening up one of these mufflers?

There should be a spring-loaded valve in the muffler which allows the passenger side exit pipe to flow at ~3500-4000rpms. It idle on a cold day, you see and feel only exhaust coming out the driver's side.

I've done a bit more research regarding these types of mufflers and it appears the design is solely to reduce noise at lower rpms and not to improve lower rpm power as I had orginially thought. The coupe muffler doesn't use a valve either.

I've curious about how the muffler would sound with the valve removed. I don't think it will sound like a coupe,
you are right the coupe does not have that velocity flapper...when my cp is warmed up and riding beween rows of houses my car emits a wonderful sound. I would not think of changing it.
Maybe sedan owners would just pick up a used cp muffler and weld it on, great sound

 

the flap is for drone & HP. you will loose hp if you remove it. infiniti wouldnt have added the flap if it didnt help with performance, you know how much more this adds to the cost . and this is why changing an exhaust on this car without a tune LOSE HP.. dynamax has a commercial about their new muffler with this internal flap.

 

Negative, the weight reduction is immediately noticeable...the sedan's exhaust is beyond restrictive, makes no sense to loose hp by making it less restrictive

 

Oh Scooby you are incorrect here, you have much to learn about the G grasshopper. If you put a cheap azz exhaust on that's possible, but I can tell you I gained HP a month or so ago when I installed the Motordyne VQ cat back exhaust. I have an appointment with UpRev next week to slap her on the dyno and see just how much the gain was. I'm adding ART pipes in a couple of weeks, and I'll get a re-flash then as well to chart stock vs. MD cat-back vs. full bolt on MD.

I think you'll be surprised at the difference in HP and torque from stock to full bolt on. I'll try to remember to post my dynos here for you to check out.


And Dave, awesome work as always. I look forward to any new thread you start because it's going to be interesting and I'm almost guaranteed to learn something I didn't know before. Thanks!!!!!

 

Or they could luck out and find a MD VQ with twin resonators. IMHO it sounds like a coupe on steroids, but no matter how you describe the tone it's pure sexxxxxx.

 

I don't think the 05-06 sedan's use this set up. If I shine a bright light in the passenger side discharge pipe, I can see it reflect off the back of the muffler from the driver side discharge pipe. They must have changed the internal design when they changed the muffler for the 05-06 years.

 

It's possible I suppose or they may have changed the location of the valve since the 05/06 canister is about 4" longer. They may have also put in a less stiff valve that opens much sooner.

On my 03/04 muffler, the driver's side pipe is about 15 3/4" deep to the back wall. When looking at my muffler pics, you'll see three spot welds near the rolled edge of the muffler, just in front of my cuts. This internal plate used to support the internal pipes. That's the wall I see behind the driver's side pipe and it forms the exhaust chamber for the passenger side pipe and valve. On the passenger side, it's about 17 3/4" deep and the back wall is the exterior wall of the canister.

 

There isn't one mention in Nissan's literature that the valve is designed to improve low rpm power. Nissan's stated purpose is:

1) Reduce exhaust noise in the lower rpms
2) Improved power under full throttle situations

As for drone, you could be right. We'll see. I do know the coupe muffler does not have a valve.

 

In 4 teh vidz

 

UPDATE

Da vids.

Okay, SCOOBY617 was right, some drone is introduced this setup. I kind of expected this myself. The only real drone effect is off the line in gears 1 and 2. First things, my mod list:

1) 05/06 sedan midpipe. It uses about a 1/2 smaller resonator than the 03/04 sedan and a bit larger than the coupe resonator.

2) HR Y-pipe

3) MD spacer and massaged lower plenum (like the MREV)

4) Revup airbox

5) 3.54 vlsd gear set

I'll be honest, this is basically like a coupe exhaust plus another 20-30%. Shockingly, it does have a warble. No rasp either. At a steady cruise, it's like stock, 20% to 30% throttle in high gear below 3500rpms can result in drone and warble. Mine is probably compounded by the fact that I don't have a spare (just a tire patch kit and pump) and the spare well is serving as an amplifier. However, the drone isn't remotely as annoying as the drone I had with my short lived Borla setup. My biggest concern is for my kids in the back. I figured out that I just have to be a little more easy on the throttle in gear 1 through 2. If I keep the shift below 2500rpms, all is good and close to where it was prior. At a cruise and any load on the highway anywhere from 65mph beyond is completely fine and tame.

With that said, the car sounds fabulous. You hear it now. It's like driving my friend's stock coupe on 11. The exhaust sound is now right in your ear with the windows down. Above 4500-5000rpms, it sounds like it did prior. That's probably where the flap opened.

Power wise, I'm not really noticing anything yet. What did happen on numerous occasions was when I punched it in 1st at 3000rpms, it resulted in significant wheelspin. That happened all three times I tried it, all different locations. It's dry out, the streets are clean from a recent rain, and the temps are in the lower 80s. Maybe the car has always done this and I just never tried. If there is power to be found, it's probably not much. I'll chime later if the ECU starts learning the change (if any).

Here are the videos. Sorry for the locusts in the background. Make sure you've got good speakers. I didn't make before videos my G sounded like every other G with a 05/06 midpipe and HR y-pipe. There are plenty of videos of that around here. Also, keep in mind the car was hot therefore the mechanical fan was engaged, making motor sound wheezy up front. I didn't make a full throttle video because there's no point.

Start, idle, rev


30% throttle from off the line to ~35mph

 

Sounds better for sure, I bet the drone isnt that bad lol. You will get used to the drone.

I have some drone from the magnaflow and no one has ever commented on it, even when it was really bad when I first got it since it was breaking in.

 

Sounds great. Can I expect to achieve this sound with a 03-04 stock Y pipe and midpipe or do I need to update to a HR Y pipe and Coupe mid pipe???

 

^ A Coupe Midpipe would make the biggest change so do that firs then see how you like it. A Coupe Midpipe is by far much easier to come by then an HR-Y

 

is this something I could do with a dremel + re-enforced cutting blades?
if so, i'm definitely going to do it, but only if i won't lose any hp/tq.

 

IMO, a die grinder is really needed to make straight, smooth cuts through the hard stainless steel. A sawsall is definitely needed to cut the valve out. I don't see any other way to cut it out because space is so limited.