Finally, got my sedan Stillen exhaust installed today (as well as my Stillen sways, but thats for another topic). Well here are my initial impressions after only 3 days and 350 miles.

INSTALLATION:
Installed at a performance shop, with myself performing 90% of the labor (friend owns a auto performance shop, and let me use their lift/tools while providing a watching eye and approval of techniques). Removal went smoothly. However, installation started off bad as the new x-pipe did not line up with the stock cats. As the cats are locked into their width position by a bracket, we had to take two large pry bars to bend the stillen x-pipe together about 5/8" to fit the lugs on the cat brackets. This is unacceptable for a premium "bolt on system". No chance that we installed upside down as the bolt pattern goes one way. Stillen told me today they use the same jig to make all mufflers. So either everyone else had the same problem, or my stock cats with their bracket were different. Anybody else? The rest of the installation went smoothly, with just a few very minor adjustments (these minor are normal with this type of large part/job). Also dissappointed, as others have mentioned, that the kit does not include new gaskets between the cats and x-pipe. I reused the stock metal gaskets (as instruction said), and just hoping they hold up (each gasket comprised of 3-4 wafer thin gaskets sandwiched together). Many types of gaskets can't be reused if they have been torqued/compressed before. Not sure about these OEM exhaust gaskets. No exhaust leaks, and the exhaust pipes clear all adjacent chassis items (not rubbing on anything).

SOUND:
Droning. Droning, and more droning. At any RPMs, if engine is under load (meaning that I am not crusing at the same speed on perfectly level ground). If on cruise control at X mph and I start up a very slight incline, you hear loud droning that is just plain annoying. I have to turn the stereo up another 4-5 notches, and can still hear the droning as it is such a low frequency that just resonates over and through everything. Even papers and coins in the door slots rattle when the exhaust drones. Such a shame as the exhaust has a wonderful sound when idling and even revving through all RPMs in neutral (under no load), but once the engine encounters load while driving, the droning takes over. Be aware sound clips on the internet sound good, and are accurate for when the engine is under no load. Stillen told me today this is normal and should "mostly" dissappear after breakin, as I only have 2 days and 300 miles to date (when I called). I just took a 120 mile, 2 hour roadtrip crusing at 75-85 and ended up fatigued with a headache.

As sound is subjective, I’ll clarify my tastes. I’ll love the low burbling sound you hear from a good American V8: corvette, mustang with a good exhaust, and BMW (not V8, but still good, especially the 330i performance package with it OEM modified exhaust). I do not like aftermarket ricey sounding fart cans. I.e. Honda civic with a huge exhaust with a high pitched annoying sound. The sedan stillen does have a sound very close to my tastes, but only under no load (i.e. sitting in my driveway at idle or reving my engine up to redline while in neutral). The low frequency droning and the resulting vibrations though are not my taste, and is not something you hear on the fine V8 engines mentioned above. Stillen also said this is not normal, and is due to being new. I think I have going to have to spend a couple hundred to Dynomat my car for sound reduction. Impatiently waiting on this one. Really disappointed with sound while under load (acceleration). I am actually a little embaressed to take my wife for a ride in the car (she has not rode in the car yet). Note that sound did not change before and after ECU reset.

PERFORMANCE:
This section is last for a reason. Stillen asked, well how do you like the performance. I said “what, can't hear you -- speak louder” (exaggerating; I was annoyed after my road trip). First, the snow has not allowed me to fully test. I have noticed a very small change (could be placebo, as haven’t fully tested yet), but to be honest, I have been so disappointed with the droning that I haven’t paid much attention. And the performance was the primary reason for this investment. I have performed the ECU reset, but have not been able to push the car hard yet.

CONCLUSION:
To early to tell, and will not make one until “broken in”, whenever that is. More updates later.

 

Please keep us posted. I am considering the exhaust for my G and while I would love to have the advertised performance gains, I don't think I want them at the expense of the drone. Thanks for the info.

Take care,

amG35
2003 Silver Sedan

 

I've had my Stillen Cat-back on for about two weeks now, and it still drones. I think that baby will drone until the cows come home. It ain't gettin' better in that regard as the miles roll by.

As far as performance is concerned, I am very satisfied! I am somewhat embarrassed to say that the sound at WOT still makes me get goose-bumps. The car accelerates like mad.

Final analysis:

High-pitched drone vs. significantly enhanced performance?

I will keep the system on the car. Improved performance wins the day. Give your wife/boss earplugs. Crank-up the stereo. Let the good times roll.

'03 G35 5AT Sedan, Garnet Fire/Willow
18x8 SSR GT1/Bridgestone PP S03 225/45/18Y
Eibach Pro-Kit Springs & Anti-Sway Kit
Stillen Cat-Back Dual Exhaust System

 

I did some more reading/research, and looks like others have had problems with the stillen x-pipe lining up with the cats. All the pressure on the x-pipe and the cats after the forced installation (x-pipe had to be bent to a narrower angle by two large crow bars to mate up with the cats) makes me wonder if some of the excessive sound and vibrations under certain engine loads are due to this constant pressure. Keep in mind that the stock Y-pipe has somewhat expensive stainless steel 5" long flexible mesh pipes that absorb vibration while offering some flexibility (at the expense of some turbulant airflow).

C'mon Stillen, you are supposed to be tops. That price premium is supposed to cover all that extensive research.

 

You are quite correct about the X-pipe not lining-up perfectly with the cats. The installation procedure you mention sounds a lot like the one my installers followed. But instead of prying at the cats with 2 big crowbars, I understand it will have been much better to loosen a bolt on the cat bracket(s), move the parts into alignment by hand, and then tighten everything up. Live and learn... Stillen could have provided a "hint" in their instructions, too.

'03 G35 5AT Sedan, Garnet Fire/Willow
18x8 SSR GT1/Bridgestone PP S03 225/45/18Y
Eibach Pro-Kit Springs & Anti-Sway Kit
Stillen Cat-Back Dual Exhaust System

 

<blockquote><font class="small">In reply to:</font><hr>

As the cats are locked into their width position by a bracket, we had to take two large pry bars to bend the stillen x-pipe together about 5/8" to fit the lugs on the cat brackets.

<hr></blockquote>I posted about this exact fitment issue a while back. The aft end of the cats are not secured with fixed brackets, they are mounted on "slip" type brackets. Just loosen the slip bolt on each cat bracket, align and bolt the X-pipe and cat flanges together, then re-tighten the cat bracket slip bolts. Simple and self-aligning if you know the secret. No need to 'persuade' with crowbars!

2004 | 6MTs | Diamond Graphite/Graphite
Upstate NY

 

My slip bracket was at the end of its "slip", or in others words would not adjust further to align. Instead of saying fixed above, should have said can't adjust further. Thanks for pointing out.

 

Little off topic, but how are you doing in autocross with the 245/45/17's Falken's?

SCCA? What class, your mods put you out of D Stock right?

<P ID="edit"><FONT class="small"><EM>Edited by cwmizner on 02/02/04 03:59 PM.</EM></FONT></P>

 

I have alot of the same mods and I have to run in STX. Do you run in SCCA stuff as well? The other stock G35's here in San Diego run in D stock.

Base 6MT Silver sedan
Stillen Exhaust
Stillen CAI
Eibach Pro Kit
Eibach Sway Bars

 

I run into this question all the time. :^ )

We have an extra set of Street Tire classes here in Houston that we run (from STA - STF) which allows a bit more flexibility in modifications. These classes are a lot like the SP class equivalents minus R tires. It's a great group and I run with mostly WRX's and Mustangs. You can read more about our street tire classes here: http://www.houscca.com/solo2/solo.aspx

'03 AT Sedan | Silver/Willow | Sport | Premium | Aerokit w/Spoiler | Nav | Injen CAI | UR Pulley | Tein Flex w/EDFC | Stillen Rotors | Cusco Sways | TS ECU | Stillen Exhaust

 

How do people in D Stock do? I haven't Autocrossed my G yet, just got it before x-mas. I used to have a Honda del Sol that I ran G stock street tire and was very succesful...

Not sure if I'll Autocross the G or not, I have a co-drive in a 95 Neon ACR, G Stock, I'll probably take the G out for time only to see how it does...

 

The other G's do OK. They are both AT so they have a bit of a disadvantage. I believe they both have the sport suspension. I tell you the Eibach springs make a big difference though. Not much body roll and the sway bars help even more. One of the guys who runs at the SD events is a poster here. His screen name is Rykoen. Maybe he will see this post and give you some more info. This is the first yaer we will have STX in San Diego so it should be interesting. I ran in ESP last year.

Base 6MT Silver sedan
Stillen Exhaust
Stillen CAI
Eibach Pro Kit
Eibach Sway Bars

 

Could you explain what you mean by a slight disadvantage? When I autocross (and 98 percent of everyone else I know that does) I shift (yes in manumatic mode) from first to second at the beginning and there's no need to ever shift again. Not only that, but I can get faster in first gear than in a manual. So how is that a disadvantage?

'03 AT Sedan | Silver/Willow | Sport | Premium | Aerokit w/Spoiler | Nav | Injen CAI | UR Pulley | Tein Flex w/EDFC | Stillen Rotors | Cusco Sways | TS ECU | Stillen Exhaust

 

I agree that with the manumatic you can go faster in 1st but the 6MT is still quicker off the line. Not by much but it is quicker. Also the small lag that the manumatic has between 1st and 2nd gear, although small, is longer than it takes a good driver to shift from 1st to 2nd in a MT. Just facts. I'm not saying I'm a better driver just what the car can do with professional drivers in each car. I also agree that once you get into 2nd gear in each, which is how most AutoX courses are driven, it is totally a drivers race.

Base 6MT Silver sedan
Stillen Exhaust
Stillen CAI
Eibach Pro Kit
Eibach Sway Bars

 

A lot of people believe what you say to be true, but the fact of the matter is that the lag is from when you hit the stick, to when it upshifts (about half a second, which you plan ahead once you learn how to use it properly) however, my foot is to the floor on the gas unlike shifting a manual where you have to let off. There is no lag from one gear to the next. So I would say the manual is at a slight disadvantage.

And as far as being quicker off the line, that's totally debatable.

'03 AT Sedan | Silver/Willow | Sport | Premium | Aerokit w/Spoiler | Nav | Injen CAI | UR Pulley | Tein Flex w/EDFC | Stillen Rotors | Cusco Sways | TS ECU | Stillen Exhaust<P ID="edit"><FONT class="small"><EM>Edited by lead_foot on 02/04/04 06:45 AM.</EM></FONT></P>