Try and find that data. I can't seem to find it.

I just measured the external diameter of my muffler with a flexible sewing-style tape measure. Right at the flange of the midpipe and muffler (muffler side) the girth of the pipe is exactly 8". Factor in Nissan's typical use of 2mm wall tubing, and you get an ID of around 2.5".

I guess I have a hard time believing Nissan changed the muffler piping diameter, but left the y-pipe and midpipe diameters unchecked. It doesn't make much engineering sense either because on NA motors, it's actually ideal to taper the exhaust towards it's exit point. This helps create better exhaust velocity by keeping the exhaust gases a little warmer. I'm not talking an extreme taper though, only about 1/4" or so.

 

It wasn't published. DaveO and I both measured his 03 and my 05 and the 05 was definitely bigger. This is strange, because DaveO measured his and it wasn't 2.5" my 05" is 2.5"

 

I have a coupe mid-pipe and the piping on the mid-pipe is the same size as the piping on the rest of the exhaust....

 

Visually looking at it you can not tell. It is so close that you must measure it which IMHO I don't think you did.

 

I did not, but whats the difference in performance, .001 in a 1/4 which is probably made up by the 25lb difference?

 

Infiniti says the ECU is more agressively tuned on the 05's as well.

 

Our personal experience(mine and my wife's) indicates that there is indeed a difference amongst the model years and engine offerings. The following information is based off our own vehicles; it's up to every one else to consider whether it may be considered representative of the sedan as a whole.

My car is an 05 6MT, rated at 298/260. The wife's car is an 04 5AT, rated at 260/260. Granted, the transmissions are different, so it's not an apples to apples comparison.

As I mentioned in another post last week, we both had our cars dynod, on the same dyno, with about 30 minutes between the two sets of pulls.

My car peaked with a 241.9whp, and 210 torque. The wife's 04 hit a 215/208. Granted, those are absolute peaks, and don't tell the whole story(for the actual curves see the attachments on this thread: https://g35driver.com/forums/g35-sedan-v35-2003-06/64639-dyno-results-various-g-z-coupes-sedans.html

Also, at the track, my car has performed in the .3 to .5 range better than the wife's. Sure, those numbers reflect different transmissions, and different drivers. But we have comparable experience at the track.

Like I said before, these numbers may not be representative of the sedans as a whole, but these numbers and times are in-line with the published numbers, and the added power does indeed result in tangible 1/4 mile time benefits.

 

My error, I just re-measured my stock 03 muffer's inlet pipe outside diameter and it's 2.5". The 05 Sedan's exhaust system does have all new part numbers. The 05 Coupe's y-pipe has a new part number... same as the Sedan's.

To the best of my knowledge, the major differences between the 03 260/260 G35 AT Sedan and the 280/270 G35 Coupe and the 287/274 350Z are:

1) The 03 AT Sedan's ECM and TCM programs are seriously detuned. (The ECMs & TCMs and their software have gradually got better as the car matured.)

2) All AT Sedans built through 06/03 - 08/03 have an engine driven "mechanical" radiator fan. An electric fan conversion is worth 8+hp.

3) All AT Sedans 03 through current 05 production have a 180F thermostat instead of the 170F all other Gs and 350Z have.

4) There's a more restrictive exhaust system. All Y-pipes are the same through the 04 model year. The Sedan midpipe/pre-muffler is larger and heavier. The Sedan's muffler is smaller, flows less cfm than the Coupe/350Z, and it's equipped with an internal valve "for increased torque" or so they say.

5) All 03, 03.5 and 04 G35's have four O2 sensors. The 04.5 and 05 ULE engines have two Air/Fuel sensors and two O2 sensors. These later cars appear to adapt (including mixture ratio self-learning control - "long term fuel trim” & "short term fuel trim".) much faster than the earlier ECMs.

 

If the 03.5-04 G sedans had an additional 8hp than my G, why is it that my 03 is trapping 97/98mph in the 1/4 mile with just a Z-pipe and MT has gotten faster trapspeeds out of the 03 5AT sedans than even the 280hp G sedan 5AT? Trap speed is the indication of available power and from what I can tell, the 03s aren't suffering from any power losses compared to the later verisons. At my track, my friend did a 14.7@96mph in his 03 bonestock G35 sedna 5AT and the guy weighs 280lbs and had stereo equipment in the back. I'm certain his 03 would perform just like mine if I was driving (100lbs lighter) and didn't have the stereo stuff. We also have another guy we know with a stock 04 G35 6MT sedan. He's a good drag racer with lots of previous experience. His best is a low 14.4@97mph with a good low 2.1 60'.

I'm not trying to argue with you at all, but it's my opinion the true power differences across the years is very minimal. Just by going off the times I see on this site, it would appear the 03s could be potentially the strongest verisons.

Now if this fan conversion really does add 8hp, then I've got another easy mod to do

 

If the early 03 Sedans don't have an electric fan, then that is an easy 8-10hp modification you can do.

 

Thank you DaveO for giving the reasons why!!! Don't question him as he has done some serious research on the cars and the differences for SportZ Mag. Like it or not Nissan handicapped the early G Sedans for what reason they only know. I have a 03 350 and 03.5 G sedan. The eats the G alive on the dyno and on the street so Thanks to Nissan for giving us less power for no real reason!!

 

Freakin Nissan bastards! Its all about the $$$...Good information Dave!

 

First off, I think DaveO offers a great service to this site and his research is much appreciated by yours truely. He's one of the few on this site that's others insightful posts and research.

Back on topic, if the 03 sedans were "handicapped", why is it they post some of the best track times and magazine times? It is very likely that Nissan did change ECM programming and such as the years progressed, but the data sure doesn't suggest that those changes were necessarily for the better when it comes to power.

Again, Motor Trend (whom corrects times for conditions to reduce bias) has tested a handful of G35 sedan 5ATs over the years. They've tested two 03s that got a 14.6@96mph and one that got a 14.6@97mph. They tested an 04 and got a 14.7@94mph and recently the 05 which got a 14.7@96mph. By looking at that data, I'd have to say the 03 might be the quicker car, especially when looking at trapspeed. I'm pretty certain my nearly stock 03 5AT could have gone low 14.3s at almost 99mph if I was running in 50 degree weather vs 70 degree weather and this is at a track 1100' above sea level. If I would have corrected my times like Motor Trend does for all their cars, my G would have run a 14.2@99mph according to them. I don't think my 03 is down on much power. Do you?

 

No one is trying to take that away from you Dave. If you want to believe the 03 is the strongest year, you go right on ahead...if you are ever in Cali, I'd be more than happy to give you a whipping at the track.


It could also appear that the 03s are potentially the strongest year because they are
1. Older, engines are more broken in and running at full potential
2. Older, so the owners have had more time to modify
3. Older, so more 03 owners have made it to the track in the last 3 years
But at the end of the day, I've driven an 03 loaner car and I'd laugh my azz off if someone told me it was faster than my 05.

 

This is my reality so I will believe it

You'll never find me in Cali. You guys are crazy over there living on the sides of mudslide prone mountains, living a smog-choked valley, etc,....yet decide to sue the fast food industry because french fries might be bad for you It's a strange world over there j/k

As for a "whipping", post up your times.

1) That could be true. My 03 only has 28K miles though and only had 24K when I raced it.
2) Z-pipe only
3) Only been to the track once. Made four passes (14.6,14.4, and two 14.5s).

My argument is not including 6MTs. In a good driver's hands, the 6MT, regardless of year, should own me by a solid .2-.3 seconds and 2mph. With that said, "good" drivers of these cars are few and far few between. Most 6MT drivers on this site are stuck in the 14.6+ range and many believing that dropping the clutch is the way to launch hard