Will the stock muffler (with stock piping) fit directly on an aftermarket x-pipes (from the cat back). Is there any real restrictions on the stock cat back x-piping? I would to get some power gains with an xpipe but dont want the coffee can look or sound like the greddy evo/stillen or any canister type muffler. Does the 2005 sedan have a variable capicity muffler. ie in higher RPMs flap opens for exhaust on the 2nd pipe?

 

No, the stock sedan muffler and mid pipe will not work with an x-pipe. As you know the stock exhaust system is not a true dual system. The Y-pipe collects from the two cats into a single collector pipe, connects to the mid-pipe, and then connects to the muffler. If you want a true dual system there are several out there in the aftermarket like Borla, Stillen, Injen. Or you could have a good muffler shop fabricate you one.

 

I just installed my stillen exhaust on fri..it sounds great...sounds nice n deep...not loud at all...if u want it to be loud u gotta get the aftermarket test pipes without cats = ) just my 2 cents

 

So can a b-pipe (from cat to stock muffer inlet pipe) not be made. Essentially a custom pipe that will allow the use of the stock muffler? Are there any crimps or restrictions between the cat and the stock muffer?

 

Being very limited with what I can do to the exhaust on my X (as in NO "Y" pipe avail) I tried the obvious and was VERY pleased. I coupled the stock Y to an '05 G35 cpe. mid pipe and bolted that directly to a Stillen single pipe rear and got, not only, great sound....BUT also the big weight loss of the frigg'n stock sdn. mid pipe. GOD what a pig! To be very honest...I don't know if I tapped into any extra HP, but I feel some improvement by the ever popular "butt o' meter". Cost ...apoprox. $450. and about an hour of work.

 

Where is the mid pipe located? between the cat and muffler? I have a 2005 sedan 6spd so wondering if our mid pipes might be different?

 

It's located between the y-pipe and the muffler. The flow goes like this...

Headers----> Cats--->Ypipe--->Mid-pipe--->Muffler

 

Sounds like you'd also be creating your own Y-pipe too. Carefull, the oem Y-pipe is awfull. You don't want to end up making your own equally awfull copy of it. Unless you can do some fancy cutting of piping and prebent mandrel bends in your garage, you'd be better off getting one of those Y-pipe's off ebay, I myself would make my own or buy the Jic Y-pipe however, but that's me.

You could have a shop make you a mid pipe, making sure it matches either a aftermarket Y-pipes output or the oem Y-pipes output. And make sure you use mandrel bends, either find a shop that can do them, or buy prebent bends off the net. Don't try and not run a premuffler of some sort, these cars sound terrible without one. You can use a 4" round Magnaflow, 18" or 22" long. Or Dynomax does make a ultraflow muffler that is a little narrower then normal, that might be worth a try to get lower noise levels then the round mufflers have.

The oem system does use crush bends, with every turn of the system the pipe diameter narrows, down to 55mm on some corners from the oem diameter of 65mm. The premuffler does have a pretty bad constriction problem of it's own. Their is a ring that the exhaust has to pass going into the premuffler, then exiting it. Going in the pipe goes down to 50mm, leaving it's 56mm. Inside, their's nothing bad, the pipe just makes a lazy turn from the middle to the side. It's the restriction going in and comming out that's the problem. By using a different muffler then your premuffler you would eliminate the the 50mm and 56mm points. What we don't know, is the diameter of the pipe going into and out of the oem coupe premuffler.

 

Ah ok I call the midpipe a b-pipe. Cool

 

Excellent thank you for the info. I am going to a shop outside of Toronto that does a lot of custom y-pipes for the Maxima community as well as b-pipes. Be great if they can develop a standard SS bolt on b-pipe that fixes all the issues in question. Also have two diameter sizes available. Let me know your input or do you think you pretty much covered it?

 

THe stillien Exhaust is Preety loud man. My Freind has one on his g35x and its deff pretty loud.

 

Loud is a subjective term but I think most would agree that the Stillen exhaust is indeed loud.