Installed the Coupe mid pipe in my Sedan a few weeks ago to see if there was a noticable difference. Well, there was definately a difference. First off, the stock sedan midpipe has a 25lb resonator attached that is flat on the bottom for aero-dynamic reasons. The sedan pipe is also very restrictive. The coupe pipe on the other hand flows much better due to the small pre-muffler (also says Nissan Calsonic on the muffler). The power increase felt like around 10 hp and throttle response was much better than the sedan's. Without the resonator, the sound was much louder inside the cabin than out. The sound is sort of a low frequency hum that drowns out low level noise. Gas mileage has gone down approx 3 mpg, and I am noticing an increase in rich fuel deposits around the exhaust tips. For those who want cheap OEM HP while not destroying your original mid-pipes, find someone who is selling their coupe mid pipe. I have not decided if I want to go back to my original mid-pipe, but it looks like I might have to. The wife is complaining that the new sound takes away from the luxury feel. Oh well...I have attached some pics of the 2 pipes.

 

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146841-stitch1.JPG

 

Better throttle response and maybe 10 hp would be ok, but a 3 mpg hit with a 'drone' wouldn't be.
Any ideas on the "rich fuel deposits"? Air/Fuel change?
I guess it may appeal to some.
GSM

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>

 

I'm sorry gsedanman, I ment carbon deposits from the rich fuel mixture. I have the Z-Pipe/Stillen setup with the HKS exhaust. The MAF/ECM is compensating for the increased air flow and the by-product is a richer mixture. I need the Techno Square mod to take care of this. Yeah, the aweful drone din is a bit annoying, aswell as the 3 MPG loss. If I was to autocross or drag the G, I would install it the day before. Install time is about 20 minutes. Hardest part is pulling the pipe mounts from the rubber hangers. Hint...Lots of WD40.

 

Glad to hear that's not fuel on the tips.
With all you're mods, it looks like a Technosquare ECU upgrade would really benefit.
About the drone-- will it go away if you pick the proper engine speed? Some of those drones come and go in a small span of mph's. (rpm's) .
I'm inclined to agree with smcallis in that the lower mpg's could be 'testing', and wouldn't be that different at constant speed.
GSM

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>

 

Sean, your are probably right about my gas mileage being affected by my heavy foot, but the noise I am experiencing is a low to mid pitched hum that starts @ 1500 RPM and get considerably louder as the RPMs build. Cool at first, but annoying there after. I did a bunch of 'Testing' on the pipe.

gsedanman, I will probably wait on the Technosquare ECU upgrade until after I get the plenum mod done.

Update: Stock mid pipe is back on and I can hear my stereo [img]/w3timages/icons/laugh.gif[/img]. Still don't know if I will get rid of the pipe, but if I do, I will let you guys know.

Mike

 

I have to wait just like you for the ecu upgrade which sux. Only I already have the plenum but now I'm waiting for an exhaust (Stillen/Borla -if one will ever come out already). Don't want to pay the extra $150 or so to have the ecu adjusted after every mod. I figure exhaust for me will be the finale for me at least performance/hp wise.

 

You might have to reset the ECU...the reason is that...you have to let the computer learn that you have a more free flowing exhaust and the reason for carbon deposits is that your computer is still thinking that it still has the restrictive midpipe. The reason i know this is cuz when my Maxima was fully stock....i used to get about 250mpg with 1/4 of gas left in the tank....but now when i opened up my intake and exhaust to more of a free flowing, i get about 270 to 300mph with 1/4 of gas left in the tank. The should not be to much of a difference between the VQ35DE and ghe VQ30DE engine other than the 0.5 liters and the variable intake manifold, that is the reason i know about these things cuz I do own a 97 Maxima and seen the same gains with people with 3.5liter engine and i know for sure there is not to much of a difference other than the drivetrain. Your gas milege shouldn't get worse....it should get better and yes probably your lead foot to hear that more raspy sound more often. You will feel a bigger difference once you open up the intake.....believe me....thats what ive seen with the VQ series engine. Especially Maxima owners from 95-2003. People seen large gains when they had the ypipe and intake combo. Gains as much as 20hp....so definantly open up your intake and you will see nice gains. Almost forgot give you ECU a couple of day to learn that you have a more free flowing a exhaust...that is when you see the nice gains i believe.

A side note evertime you do modifications to the engine make sure you reset the ECU so it can learn your new mods a lot fast than not reseting it.

Shift_DEZ' NUTS
www.midnightimpulse.com<P ID="edit"><FONT class="small"><EM>Edited by Xmax on 12/03/03 01:01 AM.</EM></FONT></P>

 

LOL[img]/w3timages/icons/laugh.gif[/img] Xmax, I am the king of ECU resets. When I installed the midpipe 3 weeks ago, I had just put in a full tank of gas and reset the ECU. About a quarter of a tank later is when I first started noticing the gas mileage difference (Been keeping a record of gas mileage since day 1). I let it go until I filled up again, and still noticed the mileage wasn't the same as before. As for opening up the intake. I don't know what you mean. I was one of, if not the first on this board to combine the Z-Pipe and Stillen box setup, so I think I have opened the intake enough for now (until I get the Plenum I want for Christmas). I am well aware of the "Learning Curve" the ECU needs when a new mod is installed. I also have an HKS muffler installed, so that could have affected the sound greatly. Anyway, I will never get rid of my HKS, so the midpipe was the one to go.

Xmax, thanks for the advice which was good, but been there, done all of that. This is however, good advice to follow for those who are new to the board.

 

i had that exact same drone that you had and it was just like you described. not good at all. this was with my 18" pos glasspack, i now have a 22" magnaflow in its place and it is 10x better. now the drone is ok and not nearly as intrusive. the drone was killing me also, if the maganflow didnt fix it, i would of put the stock pipe back on too.

 

blackonblackG, do you have any pics of the magnaflow on your midpipe?

 

i have pictures of the **** 18" glasspack, that thank god is not on my car anymore. here is the link for those pictures. http://www.imagestation.com/album/?id=4288477015
when i get home today around 4pm, i will take some pictures of my current setup for you.

 

Mike,

IMO, the major reason the Sedan's exhaust tends to "drone" is the larger enclosures (trunk and back seat area) directly above the exhaust system. If I had the problem, I'd try adding Dynamat, Brown Bread, etc. to the resonator and muffler heat shields or the area above them. I'd also consider doing the drive shaft tunnel.

DaveO

 

Thanks BlackonblackG. I look forward to the pics.

DaveO, I think my biggest noise-maker was the HKS muffler. The resonance between the HKS and the Coupe midpipe is sure to be the cause of the drone. I'm keeping the HKS and going back to the stock sedan midpipe.