The Sedan's pre-muffler (resonator) is not exactly a straight through path.

DaveO
03 G35 AT Sedan / DP / Willow / Premium / Sport / Aero / Mods / 262 & 260.7

345885-100_0001.JPG

 

"Straight through" meaning their are no chambers or wild curves. The oem premuffler only makes a slight turn from the center to the side, hardly costly if of itself.

The real issue flow wise on the oem premuffler, likely effect's the coupe mid pipe as well. From the moment the exhaust pipe enter's the premuffler body until it leaves, the pipe diameter is reduced down from 65mm to 55mm.


Splicing in a Magnaflow 4" round muffler in place of the oem premuffler keeps the piping at 65mm vs narrowing down to 55mm.


"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

Is "mid pipe" the same as test pipes....ie replacing the cat ?

 

No. I believe the midpipe is the pipe that connects in between the Y pipe (after the cats) and the muffler.



2004.5 G35-S 5AT Black/Willow - Prem, R. Spoiler, Navi, Infiniti Sport Wheels, Alum Pedals, Dark Tint, Z Tube, K&N Filter

 

Ok, so I got my Coupe midpipe installed; here are my initial impressions...

1. Sound: Wow...there's definitely a change in sound. Although I don't hear a constant "burple" at startup and idle like I hear on our '03 FX35, the exhaust note on my G35 is noticeably deeper (especially in the lower rpm's) and when I rev it it, the exhaust really comes to life. There's even a tiny backpressure "burp" or two when I rev it while in P or N...like one you would hear on a cat-back system.

2. Power: At this point, I'm still not sure if it increased HP or not, but logic tells me it did due to the fact that the Coupe midpipe is less restrictive (has a much smaller resonator and a more straight-through pipe) and it's is much lighter than the stock midpipe (with that crazy huge resonator and heat shield).

3. Other Notes: 1. The install would have taken 25 min. but the stock heat shield (directly under the driveshaft) and the small crossbar (again, directly under the driveshaft, but more toward the front of the car) were slightly in the way of the new Coupe midpipe (they were both actually just barely touching the new midpipe). Because the muffler shop guy thought these parts touching the new midpipe would cause it to rattle, he removed the heat shield and modified the crossbar by shortening it (he cut it and welded it back on to its brackets) and then reattched the crossbar so it doesn't touch the midpipe's resonator.

BTW -- Anyone know if I need to have the aluminum heat shield on it (it would reattach just above the Coupe midpipe (and I could bend it a bit so it doesn't touch either the midpipe or the driveshaft), just below the driveshaft? I kept the old parts just in case.

All-in-all, the install took about 1 hour at a cost of $100 (would have been $75, but he added $25 for the modification part)...boy, do these guys rook you or what...I think they're all crooks, but anyway, it's on and I think I'm going to stop here; I don't see any reason to add a Y pipe at this point. For a G35 with stock exhaust, the Coupe midpipe absolutely provides a deeper, slightly louder exhaust note (closer to the Coupe and FX35/45), and probably adds a few HP as well. I think it was worth the $$ spent.



'04.5 G35-S 5AT Blk/Will - Prem, Spoiler, Navi, Sport Wheels, Alum Pedals, Dark Tint, Z Tube, K&N Filter, Cpe Midpipe<P ID="edit"><FONT class="small"><EM>Edited by bsgoren on 09/21/04 01:16 PM.</EM></FONT></P>

 

I'm really jealous! I would add it but I know it will sound bad
with my HKS rear section exhaust. Good on you!

03 5AT Sedan, sunroof, splashguards, HKS muffler,
14 wire Grounding kit, Z Duct, Stillen HF/AB
Underbody rear diffusers, Drilled alum pedals,
Stillen sway bars H/H

 

Just curious... Did you see all these changes they made becouse I did the installation in my garage and did not see any of these problems. I reversed mine on a ramp and removed 4 bolts and replace the pipe. The pipe was a perfect fit. So far no problems.. My vehicle is worked hard under extreme conditions.

Sorry for asking but some muffler shops just like to drain your wallet.

 

Yes, I watched the entire time (although I agree they're all crooks! ;-). The Coupe midpipe was a perfect fit (as far as size, length, bolts, etc.), but it did touch the heat shield above (just below the crankshaft) and the small crossbar (again, just below the crankshaft). When we shook the new midpipe just a little, it banged against the two and caused a rattle (especally against the heat shield).

So, the guy removed the heat shield (which I wonder if it's necessary anyway and if so, I can put it back on since I kept all the parts) and shortened that crossbar before he put that back on. Anyone know if it's necessary?

Is your G35 Sedan and '04 or '04.5? I wonder if the '03's have the heat shield and small crossbar like mine does.



2004.5 G35-S 5AT Black/Willow - Prem, R. Spoiler, Navi, Sport Wheels, Alum. Pedals, Tint, Z Tube, K&N, Coupe Midpipe<P ID="edit"><FONT class="small"><EM>Edited by bsgoren on 09/21/04 05:06 PM.</EM></FONT></P>

 

Mine is a 03.5.. Maybe there is a difference? I did not notice a cross bar. I remenber when I took the bolts off the pipe, it just drop straight down. I would have to check agian.. Hopefully it will be with a new y-pipe. It will be most likely be the one by tuneDepot. I believe the same as the group buy.

 

The stock midpipe did just drop down, b/c the crossbar is above the (stock and now, Coupe) midpipe assembly. The rounded heat shield is of course above the stock midpipe as well (above the old stock midpipe's resonator and heat shield that's bolted onto the stock midpipe) just below the crankshaft. But, like you said, they may have added these to the '04's or '04.5 Sedans. Like I mentioned, it fit perfectly, but these 2 things were kind of in the way and it would have possibly rattled when going over bumps, etc.

Just to reiterate, it was well worth it!! I just drove the car again, and it really does have a lower, deeper exhaust note especially between 0-3000 rpm (definitely more similar to our FX35); this is the sound that should have come with our G35 Sedans to begin with...it matches the car for what it is...a very fast sports sedan (or 4-door 350Z) with a nice exhaust note to match (like the Coupe, 350Z, and FX35/45)!! ;-)



2004.5 G35-S 5AT Black/Willow - Prem, R. Spoiler, Navi, Sport Wheels, Alum. Pedals, Tint, Z Tube, K&N, Coupe Midpipe<P ID="edit"><FONT class="small"><EM>Edited by bsgoren on 09/21/04 07:41 PM.</EM></FONT></P>

 

Thanks for your reply. Do you think I should just leave the heat shied off or is it necessary and I should reattach it? I know it's just a thin piece of aluminum, but Infiniti put it there (with the stock midpipe and huge resonator) for a reason, so I'm not sure. What do you think? Thanks.

btw -- it's funny how nobody else mentioned these 2 items could be in the way when the Coupe midpipe is installed; the guy at the muffler shop kept saying..."someone must have lied to you when he said it was a 'perfect fit.' I know he just just trying to justify a higher installation cost, but I was still annoyed that what was supposed to be a simple 20 min. 'undo the old one and bolt-on the new one installation' turned out to be 1 hour 15 min. installation (with welding) costing $100. I'm sure I could have left the gray crossbar alone and just bent the heat shield a tiny bit so it didn't touch the new midpipe, but I didn't want to take any chances and since it was still on the lift, I just told him to do it (basically I just paid an extra $25 for the modifaction and welding of the crossbar) since either way, he would only do it for a $75 flat rate. So, I paid $100 + tax total. I was more annoyed with him though -- somehow, they always get $100 or more...I think they're all crooks! ;-)



2004.5 G35-S 5AT Black/Willow - Prem, R. Spoiler, Navi, Sport Wheels, Alum. Pedals, Tint, Z Tube, K&N, Coupe Midpipe<P ID="edit"><FONT class="small"><EM>Edited by bsgoren on 09/23/04 05:52 AM.</EM></FONT></P>

 

The install was merely a bolt in. I did not metion any issues as there where not any with the pipe made by Z Car Garage. It is a TRUE replacement using factory flanges, unbolt your old and insert the new. Sorry you had issues with yours but I posted weeks ago about the Z Car Garage Mid pipe and no one really cared.

03.5 Sedan/B.Sil/Prem/Wntr/Aero/Tint/Rims/Hotchkis Sways--WHERE ARE OUR PARTS!
69 Chevelle Hard Top BB/4.11's/Posi

 

Hey I was interested in the Z car garage mid pipe, you were supposed post more info. ???

"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt