BACKGROUND

So I recently bought and installed an injen SES. My initial impressions were DAMN this is awesome. The sound was fantastic at WOT, and the car sounded mean. After a few weeks though, I started to get "tired" of the sound. Anyone who's been to Toronto knows that our streets are infested with "riced out" cars, and with my injen SES, I felt that my Z - while gaining the power and looks of the Injen SES (straight tips) - had lost its exotic stock sound that separates it from the rest. It sounded a lot more like two angry 3-cylinders instead of a V6. So I started researching exhaust harmonics and downloaded every exhaust sound clip I could find.

What I realized was that every exhaust system that retained the Z's stock sound had either an X/Y-pipe on it (Nismo, Greddy etc.), OR it merged into a single muffler (Invidia G200).

WHAT I DID TO MY INJEN SES

After all that research, and knowing that the Injen system has a well-known resonator problem, I decided to go and install an X-pipe on the system where the resonators are. I wanted the Z sound back, but not only that, I wanted to get rid of the annoying drone (at least in my opinion) that the injen had at 2000-2500 rpm.

THE RESULT

My car sounded like a Z again! The first thing I noticed when firing up the system was that the uneven, rumbly idle was gone. When I rev'd it, the drone was GONE! I was impressed. But the true test came when I finally took the Z out for a spin. Adding the X-pipe not only gave me the stock Z sound back (amplified about 3-4 times though by the Injen ) but the drone was much quieter and it had moved from 2000-2500 rpm (cruising speeds) to 1500-2000!!!

So with this mod, I got the stock Z sound back, gained some torque down low (at least in theory due to scavenging effects of the x-pipe), and retained the sweet looks of the Injen SES. My butt-dyno isn't very sensitive, but in theory, I probably reduced some of the peak-HP gains that the Injen gave me... but overall, i'm satisfied

... just my 2 cents

 

hmm i just realized i may have come across sounding like an a$$ to existing injen owners... so let me add that while my modification has made me a lot happier with the sound, it's all subjective... what sounds good to me probably doesn't sound good to another person... and what sounds like drone may sound sweet to another... so take my mod with a grain of salt!

 

wow... lotta effort there dude.

got any clips? (before and after?) heh heh.

 

Hey man... yea...... took me a while to research everything, buy the parts and find a good custom exhaust shop to have the work done. My knees were shaking when they took my polished pipes to the bench saw too

anyway, my camera doesn't have an audio clip function, but I'll try to get an audio recorder of some kind and post some clips asap

 

Strife, I'm a firm believer in the x-pipe. You probably got more mid-range power, along with less droning.

 

Please tell us exactly what was done! Fabricated a custom x pipe or what? Did you still use some sort of resonators? I'd love to get amplified stock sound--if what you're saying is true, the Z will go under the knife next week.

Hopefully this didnt cost more than $100 (parts and labor).

ravi

 

Need some pics

 

thanks guys

to ravi and anyone else interested...

what I did was have the shop saw off the two resonators and install a stainless magnaflow x-muffler in its place. The total cost for the modification was about 250 CDN with parts and labor (or roughly 180-200 USD). Keep in mind that for me, it was worth it since I knew my Injen resonators probably needed to be replaced eventually anyway (spitting out fibreglass... shiny particles on the rear bumper), and a pair of 14"x4" round resonators/mufflers were going to cost about $150 regardless.

If you're interested I'll dig up the exact part number for the magnaflow x-muffler/resonator. It's essentially a dual-in/dual-out system with 2 1/4" tubing (to match the Injen), except in this case, magnaflow welded its tru-x core into it (best x-pipe available based on my research) as a crossover tube and to balance exhaust flow/sound.

I could've gone with a tru-x pipe only but I felt needed resonators in the Injen because while researching this mod, I also realized that any exhaust system for the Z that didn't have a resonator upstream from the mufflers ended up sounding raspy. The magnaflow muffler was a perfect fit since it served all of my requirements... removing rasp as a resonator, straight through design, balance exhaust flow between the two sides, and based on its position in the exhaust stream, it should in theory be able to scavenge some low-end torque for me as well.

The only thing I wasn't able to do, was to have the whole thing TIG welded (which would cost a heck of a lot more than $250 in labour alone)... but I had the shop spray their standard MIG welds with silver ceramic paint to inhibit rust... hopefully I won't need to have the system rewelded for at least a couple of years

 

I'll post clips as soon as I can

the best way of describing the sound is a deeper, louder version of the stock Z. You can definitely still tell from the sound that I have an Injen... but the difference is, the stock Z sound is retained in all but the deepest, droniest RPM ranges (below 2000 rpm)

even then, I'm inclined to believe that the stock Z is buried in that deep grumble somewhere It's just masked by (what I consider) drone

 

Well known eh. How come I don't know about it? You got any posts that talk about it?

 

Very interesting. Thanks for the information. As far as backpressure/flow is concerned, do you think its just as effective as the original "true dual" design?

Also, you mentioned MIG welding...does that rust or ever break off? I'd hate to have an exhaust leak. I probably will end up not doing this, b/c the Injen sounds fine to me--but knowing I could modifiy it later is interesting.

Good job on taking a chance Strife!

ravi

 

King Tut: the resonator problem affected many of the earlier Injen SES systems... but you're right, I shouldn't make a blanketing statement like that, especially since Injen has since improved their design and fixed the issue with their newer production runs. But just from my experience, I didn't expect my system to have any problems until I started noticing sparkly deposits on my rear bumper.

Ravi: np! In terms of backpressure, the x-pipe should in theory decrease flow a little bit... the reason being that the exhaust gases are no longer travelling in a straight line but are instead forced to crash into one another at the x-pipe junction. However, having the exhaust gases crash into one another is what I wanted, since it's what cancels out the droning harmonics. Anyway I suspect it's this slight increase in back-pressure, combined with scavenging that is making me feel like I regained some low-end torque. I only had the modification done two days ago so I haven't had a chance to go WOT, but like I said earlier... I wouldn't be surprised if I gained sound/low end torque at the expense of peak hp

 

Damn, I'm very tempted with this information. Let me call some shops and put some thought into this. As far as the welding issue, should I be concerned about it falling apart or something?

ravi

 

oh and about the MIG welds... they're not ideal, since they use mild steel as the welding compound... but when done correctly, they aren't terribly prone to rust either. On my old car, I had a custom stainless exhaust system with an HKS titanium muffler welded on using MIG welds and it lasted a touch over 3 years before the welds started to rust and leak. That's in Toronto where it snows 4 months a year and the roads are covered in salt for about the same amount of time.

When the welds finally gave up, it only cost me about 25 CDN to have it touched up. From what I've been told, it's the rust/corrosion of the welds on the inside that are alot more worrisome than the rust/corrosion on the outside. I think the key is to also catch the broken welds quickly, as soon as you notice a change in sound, reason being - if the welds all fail and you don't notice it, you'll be out an entire magnaflow resonator

 

whats the part number for the x pipe really nterested glad your brought this to everyones attention and good find!!!

 

Strife, good job, good info!

welding MIG or TIG, its not that important for an exhaust. Yea, TIG is better for thin stuff.

The real issue is the weld filler rod. Since the injen SES is, well, STAINLESS...the rod should be...you guessed it...STAINLESS! Primer or no primer, it's still going to corrode at the weld filler unless they use a stainless rod. It's just as easy for a shop to use the right filler rod as use the wrong filler rod. If they don't have the right filler rod....ask 'em to buy it (and change you an extra $5 if they must).
It just amazes me what some shops will pass off as quality. There is nothing quality about welding stainless with a carbon steel rod.

 

thanks again guys... and bwilliams... good info on the filler rod; the shop did in fact use stainless rod (not sure about the primer though)

anyway, I finally got a chance to record a couple sound clips. I had to do these by myself today, and the position of the mic was probably less than optimal (I used a laptop and put it in the trunk)

can someone help me host?

 

btw they're quite small... only ~ 100 kbs each

 

Courtesy of Llare on 350zmotoring (thanks!)

www.350zos.com/injen/strifeSES-inside.mp3

www.350zos.com/injen/strifeSES-outside.mp3

I'll get some better clips this weekend... maybe a video too

 

Nice.

Do you have any pics of X-pipe?

On side note, I have the SES and same thing happened to me. While I loved the sound at first, I was getting paranoid later it was sounding rice. Until I heard it from outside... Fell in love all-over again and never looked back. Actually, since that day I basically can't hear the drone anymore... suspect that part of it was in my head(it's like when someone is snoring, it appears to get louder and louder, lol). Anyway, I wouldn't buy any other exhaust should I do it again.