Exhaust questions

[ej205scoob]

Hi guys, New to the scion TC, not new to performance (drive a wrx). I have some questions about the TC.

First off what is the best performing Cat-back?
Secondly when do the stock headers become a restriction? If i need to replace them what do you think of the DC header? I plan to go trd s/c. Any advice is appreciated. Thanks.

-Mike

[bwood87]

I do not know what would be the best, but you are going to be looking for a 2.5" exhaust since you are going S/C.

The stock exhaust manifold is very restrictive. Each exhaust port meshes into your cat within a few inches of exiting the engine. If you look under the heat shield you can see what I mean.
The DC headers would not be my first choice but certainly better than the stock manifold. As with most headers out for the tC right now, DC is only 4-1. Some places advertise it as 4-2-1, but its not. The only true 4-2-1 that I know of is by Weapon-R.

[ej205scoob]

Thanks. What do you think of the Borla?

[bwood87]

Borla is always a good choice they are a well known brand and from what I read they make quality stuff.

[navylife59]

TRD Sparks sells the Borla, along with, the TRD. Greddy, HKS, and Magna Flow sell quality units. The sound, well that subjective. Replace the OEM header and you have a loud, raspy exhaust no matter what brand. The fault is the OEM resonator is not designed with those mufflers/flow. If replacing the header, then you should look into cat-backs with tuned resonators like Greddy or Magnaflow. Just for starts, the easiest and cheapest is to replace the OEM s-pipe with an Invidia or custom unit. BTW Meagan Racing is poor design/quality and ZPI is no longer in business.

As bwood87 stated, stay away from 4-1 headers unless your going full drag. Also, don't go with those huge turbo mufflers. They are for turbos, not N/A or S/C. N/A and S/C motors need some backpressure for exhaust scavenging for low-end torque.

[StreetracerJay]

I have the s/c with the greddy axle back and it sound great. I would recomend greddy.

[hotrice]

well i put the megan header on today with the greddy axle back and that thing is ungodly loud!. crappy thing is i tried to take the o2 sensor out of the old one and turns out toyota cross threaded the thing in so now i have to buy a new o2 sensor. navy got any suggestions on how to tone down the raspyness?

[navylife59]

A couple of bananas......

What is your complete exhaust setup? What are you running for the s-pipe and mid-pipe?

[bdis3]

I have the Weapon r header and the Magnaflow exhaust. It sounds pretty good. I am also gettin supercharged so when its done ill put up some clips.

[hotrice]

well right now i'm not running an s-pipe just header and axle back

[montani1976]

does the exhaust set up change from 07 to 08?....im wondering because there are so many 04-07 setups and if i buy one i want it to fit....and help is greatly appreciated

[navylife59]

2005 thru 2009 models have exactly the same exahust. You can safely order your exhaust parts.

[frc19]

I personally like the megan drift spec cat back, even though i have the TRD.

As for the header i myself am currently looking for one and i think the best bet is the MMW header even though its a bit pricy. It is however the only 4-2-1 header out there rather than the 4-1, another thing to look at.

Ive heard alot of complaints about the DC header and the only other one ive looked into in the Megan(which i dont thinks fits if you have the s/c). The most common thing i see with that is it tends to be a bit raspy...as do all headers on a tc

[navylife59]

That is the 4-1 setup. It does not take advantage of the exhaust scavaging as the 4-2-1 does. You will still get some raspiness if you removed the secondary cat.

[Redneck4csa]

That is the 4-1 setup. It does not take advantage of the exhaust scavaging as the 4-2-1 does. You will still get some raspiness if you removed the secondary cat.

I just want a nice header and s-pipe setup that will sound just like the TRD but louder. I know, it's impossible. That's just what I want.

[navylife59]

Not impossible, just expensive. It is all a matter of tuning with the correct resonator type/size and muffler combination. This is accomplished by control the frequency harmonics and exhaust flow. That is what the OEM's do with those boxes hanging off the factory intakes. They are Heimholtz resonators. Mufflers to put it in simpler terms. There is equations for calculating this, but I have not figured out what they are yet. Anyone who is an Acoustical Engineer should know these.

I too love the TRD sound and was sad to give it up. It gave the tC some balls. No, not the kind that hangs off a trailer hitch.

[Redneck4csa]

Not impossible, just expensive. It is all a matter of tuning with the correct resonator type/size and muffler combination. This is accomplished by control the frequency harmonics and exhaust flow. That is what the OEM's do with those boxes hanging off the factory intakes. They are Heimholtz resonators. Mufflers to put it in simpler terms. There is equations for calculating this, but I have not figured out what they are yet. Anyone who is an Acoustical Engineer should know these.

I too love the TRD sound and was sad to give it up. It gave the tC some balls. No, not the kind that hangs off a trailer hitch.

Well, I know you have a complete set up on yours, Navy. Any chance you would have a video of that? I want something deep and smooth like the TRD, but really loud. I can't stand the raspy exhausts that I commonly hear.

[navylife59]

Well mine was a full setup custom made at Jotech. The guy (no longer working there) used vibrant mandrel bent tubing that he tig welded together on the bench. That way it could be tucked as close as possible w/o hitting anything. My s-pipe is wrapped and tucked up high.

The sound is awesome and deep at idle and normal low-speed driving. When my timing is right, it sounds damn mean with no rasp at all. I have been having issues with the ECM pulling back timing no matter what the Greddy has mapped. This is quite perplexing. When the ignition and/or cam timing is in full retard I get a nasty rasp around 4K with throttle 60% or better.

We used to identical 12" Top Speed resonators. In hind sight, I believe that utilizing identical lengths causes a frequency shift in the second resonator that reflects back into the upstream exhaust or its a combination frequency shift that multiplies in the HKS PowerMax muffler causing resonance that pings against the muffler wall. Acoustical energy in an exhaust system follows the same laws as that of audio frequency as of a subwoofer enclosure. It is all conjecture without any imperical data. Simply put, one should be able to change the resonant frequency of an exhaust not by altering sizes of a single or multiple resonators.

[Redneck4csa]

Well mine was a full setup custom made at Jotech. The guy (no longer working there) used vibrant mandrel bent tubing that he tig welded together on the bench. That way it could be tucked as close as possible w/o hitting anything. My s-pipe is wrapped and tucked up high.

The sound is awesome and deep at idle and normal low-speed driving. When my timing is right, it sounds damn mean with no rasp at all. I have been having issues with the ECM pulling back timing no matter what the Greddy has mapped. This is quite perplexing. When the ignition and/or cam timing is in full retard I get a nasty rasp around 4K with throttle 60% or better.

We used to identical 12" Top Speed resonators. In hind sight, I believe that utilizing identical lengths causes a frequency shift in the second resonator that reflects back into the upstream exhaust or its a combination frequency shift that multiplies in the HKS PowerMax muffler causing resonance that pings against the muffler wall. Acoustical energy in an exhaust system follows the same laws as that of audio frequency as of a subwoofer enclosure. It is all conjecture without any imperical data. Simply put, one should be able to change the resonant frequency of an exhaust not by altering sizes of a single or multiple resonators.

Is there any way we could hear it?

[navylife59]

Sorry, but me and my baby are separated by 500 miles right now. I will try to get a good sound clip when I get back to Texas in a few days.