Exhaust noob here so be nice.

What exactly is the purpose of the y pipe? And, why is it smaller diameter than what comes in and comes out of it? Is it noise, emissions, there must be a reason why nissan designed it the way they did. Also, is the x pipe better for any other reason than being larger diameter?
Some education would be appreciated.

mike_of_earth wrote:They cut just in in front of the resonators and back where it splits to the mufflers. See images;

Hey guys, I read somewhere that some folks installed the X pipe before the resonators, not after. I am curious as to what the inside of the resonators look like. (looking through the openings) Is there enough restriction (like the Y pipe) in the resonators to warrant replacing them as well? From looking at the picture, it looks like it would be pretty straight forward to just make the cuts before the resonators. I listened to the sound clips; during the revs it sounds like a little backfiring going on, and I was wondering if the resonators would help moderate that...anyone have a sound clip with X pipe installed but stock resonators and cans?

Just an FYI, Stillen has it on sale today for $950.

AlphaSnacks wrote:I will say that without a shadow of a doubt, deleting that Y-pipe adds a lot of power. Low-end throttle response is really snappy now, and the torque has increased. I can make some really good passes in 7th gear on the highway without having to force the trans to shift down. It's very effortless.

Also, and this is most important, stock the motor doesn't continue to make more power past ~5900RPM. Now it pulls all the way to redline without any flatspots. It astounds me that Infiniti would fit this car with such a hunk of junk exhaust and rob the car of its potential.

As I mentioned earlier, I ended up doing the same thing. I had the shop remove the heat shields/insulation and cut the Y-pipe/resonator section out in one piece like the picture mike posted:

I was debating on going further and taking the post cats and flex pipe out as well, but I chickened out. They tied the exhaust back in with a 2" X pipe and 2" straight pipes back to the stock mufflers. The result is as exactly as you described. The sound inside is really no different, which is good...get on it and you can hear the difference. The inside tubes of the resonators choke down to 1-3/4", and resemble a glass pack without the louvers, just perforated metal instead:

With that said, I am now thinking about going back and having them take out the 2 post cats as well. I'm also thinking that the flex pipes are important to avoid cabin drone, so I will probably keep them. Main thing is avoiding any emission issues at inspection time. I read where TheMajesticKing did this and had no check engine light. Just wanted to make sure before I proceed.

TheMajesticKing wrote:Yes. You're not interfering with the emissions system by doing a muffler delete. However, the stock ypipe has cats built into it so technically a custom ypipe would not be smog compliant. BUT I just recently went through emissions here in MD and passed with no problems. There are 2 sets of cats (4 total) on the M56. The precats are located in the exhaust manifolds and they are VERY restrictive. So I couldn't see failing a smog check as long as those are still installed.
I have the custom ypipe now and there is no smoke or smell from my exhaust at all, and most importantly, no check engine light.

I may be pulling the trigger on a custom y-pipe from the CAT's back (California); you said the precats are very restrictive, how restrictive are the CAT's? Would there be any performance gain in replacing the piping from the cats to the flange? I have a full Stillen cat back already installed so the remaining exhaust system is already in place and have UpRev Tuner version.

I just got my M56s yesterday. First time I have ever seen or heard one run in person. I def will be doing some type of exhaust setup because it is just too quiet stock. I was thinking about magna flow because of the deep rumble they have. I don't want it loud loud but enough to know it has a V8 sitting at idle and when I get on it without drone issues. What are other options outside of Stillen and straight pipes? I don't want Stillen because apparently it doesn't add any horsepower according to other owners who have added it to their M cars. I am in NC so last time I checked we could not cut off the cats and put straight pipes because of state regulations. Any good muffler options or cat back systems you guys would recommend to checkout?

Unfortunately there isn't many options for the M56. There is rumors of another company being contacted to see if they can make one but right now you just have the stillen, straight pipes, and OEM Infiniti mufflers with some custom piping after the cat and before the mufflers (search for the thread on the first page).

Ilya wrote:Unfortunately there isn't many options for the M56. There is rumors of another company being contacted to see if they can make one but right now you just have the stillen, straight pipes, and OEM Infiniti mufflers with some custom piping after the cat and before the mufflers (search for the thread on the first page).

Thanks Ilya. I just found another post by a member who has put some Magna flows on his M56 with a X-pipe. When I get a break I am going to watch the videos he has posted to see if I like the sound.

walt1227 wrote:...I am in NC so last time I checked we could not cut off the cats and put straight pipes because of state regulations. Any good muffler options or cat back systems you guys would recommend to checkout?

The main cats (bolted directly to the exhaust manifolds) that have the O2 sensors connected are the ones you have to leave in place. The secondary cats that are part of the Y-pipe/resonator assembly can be deleted. I live in Forsyth County. NO check engine light, passes emissions no problem. Gas mileage even got a little better. I am currently running the stock tune but that is going to change real soon.

IMHO, just adding a performance muffler by itself will only get you a deeper sound, not real performance gains. I also believe that adding a cat back system like the Stillen or Magnaflow will only get you real performance gains IF you add a custom tune like the Uprev or Bullydog. Adding straight pipes with a good performance muffler plus a custom tune will get you the best performance and sound.

It depends on what you are looking to get out of your car. It may take a couple of set ups to find the one you like. I changed my exhaust three times before I was happy, as posted in the OEM Sport Muffler thread. Anyway, good luck in whatever you decide to do!

The stillen exhaust sounds really nice and not loud at all and there also another write on an intake viewtopic.php?f=1247&t=604534&e=1&view=unread#unread
for the M56 that we are currently trying to get which will give more hp, i personally am waiting for the intake before installing the uprev.

I myself am still leaning towards the Stillen exhaust although it's a little pricier. It just has a nice overall sound. I'd go the OEM sport muffler route if they also sold a sport mid-pipe section...but I feel like no one in my area will be able to make me a nice enough set that won't have some stupid sound to it.

Ilya wrote:I myself am still leaning towards the Stillen exhaust although it's a little pricier. It just has a nice overall sound. I'd go the OEM sport muffler route if they also sold a sport mid-pipe section...but I feel like no one in my area will be able to make me a nice enough set that won't have some stupid sound to it.

And with that last line u wrote, it should be reason enough to go the Stillen route. It has a tried n true nice sound and it's not "annoyingly" loud. Maybe not loud enough for some as I have read on the forums but it sounds like a quality exhaust n not a tin can. Btw...on my set up before my Uprev tune I would get some backfire while reving it up. I was a bit disappointed in that but after the Uprev was installed, no more backfire issue. Just an FYI to anyone having that issue that's not tuned.

Does anyone with the Stillen exhaust have any ideal how loud it gets compared to say a stock mustang or camaro? Is it around that volume or louder? I could live with the quite exhaust but I want to hear that rumble a little more than it is now. Also i don't know of any exhaust system especially after market that doesn't add at least 3-7 more hp and tq. I've lived half my life around nothing but fast V8 cars, camaro, trans am, mustang, etc. Adding an aftermarket exhaust always gave a little bit of performance boost. Does it make a huge difference?......no but it does add something over plain stock.

I also live in NC. I have a 2011 m56s and in about 2-3 weeks or so I plan on cutting the stock exhaust off behind the 2nd cats and rinning new piping into a magnaflow x-pipe with magnaflow mufflers out the back with no resonator. Only thing I'm guessing now is whether I want to run 2.25 or 2.5 in piping.

So far I've kept the car stock but wanted wasn't pleased with how quiet so I figured I'd take it one step at a time amd remove just the resonators first and keep the stock mufflers, just didn't want to accidentally make it too loud or make it any slower.  Lost a little on the bottom end, not too bad,but helps a little on the top end This made a great improvement over stock and sounds imo how loud it should be from the factory similar to a factory camaro's or a corvette. Not as loud as the challengers. At this point you can definately tell it's got a v8 just by doing this but I got ued to it quickly and wanted it louder. I wasn't too worried about how loud it'd be in the car since these cars are insulated from noise pretty good I feel like. So before I hacked anymore of the exhaust off I decided for s*** and giggles I'd try the "free" washer mod. It took a little experimenting with how many washers I used but that's how I'm Rollin right now and it's perfect to me, sounds like a mustang sort of. Little bit of drone on moderate acceleration which doesn't bother me and you can definately feel a little rumble in the car at idle. The cold starts sound amazing in open loop, definately turns heads, and then quiets down to a very nice sounding idle like a stock Titans'.
This week I'm going further though since I believe that removing the post cats and putting 2.5" in its place with an x-pipe will let this engine gain at least 8-10hp, I just hoping I like the noise it makes. I plan. On still keeping the stock mufflers since I feel the most restrictive parts are the resonators an cats and I don't want to change the mufflers yet since they probably won't add any performance and I'll most likely be happy with how loud it is after doing this. Oh, and I plan on deleting the washer mod after doing this as well to see what it will sound like. Didn't really want to drop the money for a stillen kit so I've been going the cheaper route and have been changing the exhaust little by little until the sound I like is achieved. I get tons of compliments and love how it sounds right now but figured I'm getting used to how fast the car is and want to start making some more power and this factory exhaust is definitely holding this car back bigtime. I plan on getting upRev very soon too.

Can you post some videos if you have the time of your exhaust sound now with just the resonators removed on stock mufflers? I'm like you really don't want to spend the money on the whole exhaust just yet because I'm waiting for the intake kit to come out hopefully by the end of the month

DRM56 wrote:I also live in NC. I have a 2011 m56s and in about 2-3 weeks or so I plan on cutting the stock exhaust off behind the 2nd cats and rinning new piping into a magnaflow x-pipe with magnaflow mufflers out the back with no resonator. Only thing I'm guessing now is whether I want to run 2.25 or 2.5 in piping.

Where in NC are you located? I am in the Cary-Durham area.

I stay in Ahoskie, but I have some family in Raleigh and some cousins in Cary and Fuquay-Varina. We will have to meet up sometime and checkout each others rides.

DRM56 wrote:I stay in Ahoskie, but I have some family in Raleigh and some cousins in Cary and Fuquay-Varina. We will have to meet up sometime and checkout each others rides.

Sounds like a plan. I saw a guy driving a white M56S today in Durham with full Aero kit. I would love to meet more m owners around the area.

Man I been hoping they would have a meet or something for m owners in NC/VA area. Esp M56 because they are very rare. So many people ask me what da heck is a M56s or they say I didn't know they made anything past M37.

DRM56 wrote:Man I been hoping they would have a meet or something for m owners in NC/VA area. Esp M56 because they are very rare. So many people ask me what da heck is a M56s or they say I didn't know they made anything past M37.

I had a guy driving a M5 say the same thing yesterday lol. I have only seen two M56S or M56 period besides mine. I have the only black one so far in the area that I have seen. The others were that white one and a Platinum Graphite with aftermarket rims owned by a doctor who traded it in this year.

There is a black M37S in Durham with arro kit that was just brought. I saw it house shopping a few weeks ago.

Yeah I got 22 inch concave wheels on mine. 22x9 in the front and 22x10.5 in the rear. Liquid platinum color. I hope they start making more performance parts for our cars. I joined the list to get the new intake kit from r2c. Suppose to come n out this month sometime

DRM56 wrote:Yeah I got 22 inch concave wheels on mine. 22x9 in the front and 22x10.5 in the rear. Liquid platinum color. I hope they start making more performance parts for our cars. I joined the list to get the new intake kit from r2c. Suppose to come n out this month sometime

I bet it looks nice! Post some pictures in the pictures forum when you get time. Yeah I heard about those intake kits. I probably will check it out once members test them on their M's.

Here ya go,I'll try and get one tomorrow of a cold start. Plus ill see if I can get one with just the deleted resonators and no washer mod, its much quieter than this

http://www.youtube.com/watch?v=usvD3jytmKA

Man that damn thang sound good. I really didn't expect for it to sound like that but it has a clean crisp sound. May be doing mine like that instead for the time being.

How many washers did you use for your muffler delete?

DRM56 wrote:Man that damn thang sound good. I really didn't expect for it to sound like that but it has a clean crisp sound. May be doing mine like that instead for the time being.

Thanks man,the downshifts sound nasty and at idle it's just loud enough so that you can hear it in the house when i pull up but not ridiculously loud that you can hear me come into the neighborhood

DRM56 wrote:How many washers did you use for your muffler delete?

think I used a dollar in quarters in each on each flange at first but I think I went down to 75cents lol. You'll have to play around with how many washers you use. The trick is to delete the mufflers slightly and only allow a certain amount to come out of the flange so it's not too loud. I mean loud is fine with me so much as it sounds good but if u open the flanges up too much sounds like crap imo...since it wasn't gonna cost me anything to try besides the $50 to delete the resonators I figured what the hell and give it a try and low and behold i actually like it alot. Almost scared of how loud it'll be when I replace the post cats with 2.5in and add an x-pipe next week, I'll probably end up removing the washers and let it flow thru the mufflers. But that'll be something ill play with also after gettin it done, might leave 1 quarter in there lol we'll see, but I'm definitely gonna get it tuned asap once the exhaust is done.

I love my X pipe/cutouts and post cat/resonator/Y-pipe delete. Quiet when you want it to be, awaken the dead ith the flip of a switch. I opened them on a 5.0L Mustang that was playing around with me a couple of weeks ago. He was quite shocked when I pulled on him out of the greenlight. His car was loud, mine louder!

https://www.youtube.com/watch?v=EzNDbBjm1yg