welding on a second Cat further down the exhaust

[mav1178]

Originally Posted by Tristor

Don't add a cat, consider using a dual resonated front pipe, resonators will help more that the cat, or go back to your stock front pipe which has a cat in it.

OP has only UEL headers + overpipe. everything else is stock...

[RToyo86]

Originally Posted by mav1178

for what you want to do, you're better off buying a 2017+ exhaust manifold and gutting the cat.

seems like you want the sound "benefits" of a stock setup without the flow restriction...

or you can go with a full setup like Apexi.

https://www.ft86club.com/forums/showthread.php?t=103338

How much louder is a gutted OE header over an untouched one?

[mav1178]

Originally Posted by RToyo86

How much louder is a gutted OE header over an untouched one?

probably about the same... the volume of the stock catalytic converter is the main reason why it's quiet, not because it's more restrictive.

aftermarket cats are always smaller and do not provide any sound suppression capability of any kind.

when it comes to exhaust sound, the total volume of resonators in the entire system is more important than how many baffles or "restrictions" there are.

[new2subaru]

Originally Posted by mav1178

seems like you want the sound "benefits" of a stock setup without the flow restriction...

or you can go with a full setup like Apexi.

https://www.ft86club.com/forums/showthread.php?t=103338

Do these ever go on sale?

[86MLR]

After testing a Tomei UEL header against a 17+ decated header, and finding no real difference in performance (the OEM was slightly better up top, which I put down to better scavenging), apart from alot more noise, I replaced the 17+ decated header.

Same performance, less noise.

Those UEL headers are loud, and ridiculously loud on cold start, compared to the 4:2:1 OEM EL header.

The OEM header is actually designed very well, it isn't pretty, and could be improved, but, at what cost for what gain.

If you want a aftermarket header for a NA engine, the only thing that I would try would be a nice 4:2:1, pick you lengths for your application, a ACE 250 looks good for my use, I cannot justify the cost to see the difference between it and the punched out OEM, to get that puppy shipped to my door here in AU would cost a kidney.

Why did I go UEL in the first place you may ask, curiosity, there was so much, "UEL will give more torque", or "UEL makes no real difference" I had to try one for myself, against common sense and physics, mainly boredom and the need to play.

A UEL header design is not what you end up with if you use fluid/thermal dynamic in the design process.

I 100% believe it is marketing and the sound that people go for, "sounds like a STI BRO, only slower".

Same same with the focus on the torque dip bandwagon, it isn't really the issue people make out, but if you can sell a few parts.....who is physics to stand in the way of good marketing.

But, don't listen to me, I'm just another punter on the interwebs voicing my findings and opinionated opinions, do some research, check out some point end track twins, make some informed decisions based off sound engineering principles.

As to the overpipe increasing noise, I noticed zero change in noise going from OEM overpipe to a 2.5" overpipe.

Disclaimer: my sound meter is a phone app so accuracy may be a issue.

UEL header and 2.5" catless resonated frontpipe is loud, even with OEM midpipe and muffler.

OEM full catless (punched out) exhaust supports about 200hpatw with a good tune.

If you want as much power as you can get you will need to lose the cats, yes, even 100-200 cell cats are a noticable restriction.

And like always, opinions may vary.......like what people like with their exhaust noise I suppose........

Wow, that got overly involved

[86MLR]

Played with the sound meter, full catless OEM exhaust apart from a 2.5" overpipe.
Cold start 73db
Idle 65db
7k rpm 85db

198hpatw.

I'm selling the Tomei UEL header to a local guy so it wasn't to costly of a test.

Anyone else have any db numbers?

[churchx]

Just like with different dynos, numbers from others will be of little help if not outright misleading.
You have to eliminate big bunch of variables to ensure numbers can be compared. Same recording tech, same config/tunable for rec. tech, same methodology (eg. distance/angle/direction), or at very least same baseline (eg. stock) for there to be to compare/base on. If anything, loudness measurement and sound recording can be gamed much more then dyno runs, leading to completely wrong verdict if comparing numbers from different parties w/o going long way to eliminate possible differences skewing results. And as many might be in it just for fun, they won't care for that extra PITA or spendings on recording equipment & methodology to make measurements objectively comparable, so what will be left, just subjective view of individual. "louder", "quieter", "too loud", "too quiet" which all differs from person to person and so on ..

[bfrank1972]

It is also not just what is coming out of the pipes. Noise from an aftermarket header itself can be significant over a stock unit because the heat shield on the stock header dampens noise under your feet. Our cars have a thin metal underlay that can reflect that noise back into the cabin too.

OP you sure that rasp is not vibration of the overpipe or some other component touching the chassis?

Sent from my SM-G965U using Tapatalk

[evoto86]

Originally Posted by bfrank1972

It is also not just what is coming out of the pipes. Noise from an aftermarket header itself can be significant over a stock unit because the heat shield on the stock header dampens noise under your feet. Our cars have a thin metal underlay that can reflect that noise back into the cabin too.

OP you sure that rasp is not vibration of the overpipe or some other component touching the chassis?

Sent from my SM-G965U using Tapatalk

It sounds like just exhaust noise to me but then again it's hard to tell because the twins make all sorts of noises 😂

[Stang70Fastback]

Originally Posted by ls1ac

A cat requires a certain temp to work, like near the engine. They are also expensive, and have to have contact with the exhaust gasses so the passages have to be small. (read restrictive). If sound is the issue see above, a resonator will probably help. Again nearer the engine is usually best as the pulses are more definded, but anywhere in the exhaust will help.

Ever since I added my ACE header and overpipe, my exhaust has become raspier than I'd like above 4,000 RPM. Still have my Fujitsubo Catback, but the stock Front Pipe. Some folks have suggested a dual-resonated Front pipe, like the Fujitsubo to match my catback, or even the JDL Ultra Quiet. Any thoughts on whether that might help? I'm a bit apprehensive as I also am not PARTICULARLY interested in removing my last cat and having a super-stinky exhaust.

Here's how it sounds at present:

[ame]https://www.youtube.com/watch?v=uW1AeeY4j_k&t=4s[/ame]

[wparsons]

Originally Posted by evoto86

At low RPM especially from first to second when I'm setting off from the lights the sound can be extremely raspy give off an off based frequency, what bothers me is the lack of consistent sound build up like with a stock exhaust. I can deal with a bit of loud I just don't like the random flactuations I get out the back at low RPM. I don't want to spend money on a catback because my cars just a daily but I really want to keep the benifets of a catless header because the cars much more streetable with the extra torque and power.

The stock catback is known to get raspy and sound funny with a catless header. An ultra quiet (catted and resonated) front pipe might help, but that's not going to be super cheap.

[bfrank1972]

Originally Posted by evoto86

It sounds like just exhaust noise to me but then again it's hard to tell because the twins make all sorts of noises 😂

Yeah might be - I just remember when I first installed my headers I had the issue where it would buzz just a bit when taking off. It sorta sounded raspy, but you can really tell if you pull off your undertray and rev a bit while listening under the car. Real rasp comes out the back, vibration you can hear it under the car with the tray removed.

[mav1178]

Originally Posted by evoto86

It sounds like just exhaust noise to me but then again it's hard to tell because the twins make all sorts of noises ��

[ame]https://www.youtube.com/watch?v=sWxvQXjjgaQ[/ame]

This is a completely catless setup with an exhaust that is similar to stock in terms of design (baffles instead of perforated pipe straight through). Notice that "rattle"? With a stock catted header that rattle is not there...

As you can hear, there's some rattle at some RPMs. Under load, it's a bit more pronounced... but there's no real way to get rid of this.

Based on my experience, some of these smaller noises are simply just different parts (that were R&D'd individually) that, when put together, have weird vibrations or rattles at odd frequencies that didn't exist in the stock setup.

People tend to not give the factory exhaust enough credit... it's really more than sound suppression, it's also about giving the car character without "defects" in quality.

It's very hard to say definitely what issue you're having without someone looking at the car in person, but my recommendation leans towards 2017+ gutted header and stock everything else. Or just a quiet catback + gutted header with the stock front pipe, but there may be some weird resonance or rattle that will show up in the stock muffler if you go catless in the front. YMMV.

[bfrank1972]

Originally Posted by mav1178

This is a completely catless setup with an exhaust that is similar to stock in terms of design (baffles instead of perforated pipe straight through). Notice that "rattle"? With a stock catted header that rattle is not there...

As you can hear, there's some rattle at some RPMs. Under load, it's a bit more pronounced... but there's no real way to get rid of this.

Based on my experience, some of these smaller noises are simply just different parts (that were R&D'd individually) that, when put together, have weird vibrations or rattles at odd frequencies that didn't exist in the stock setup.

People tend to not give the factory exhaust enough credit... it's really more than sound suppression, it's also about giving the car character without "defects" in quality.

It's very hard to say definitely what issue you're having without someone looking at the car in person, but my recommendation leans towards 2017+ gutted header and stock everything else. Or just a quiet catback + gutted header with the stock front pipe, but there may be some weird resonance or rattle that will show up in the stock muffler if you go catless in the front. YMMV.

Lol I wish I had a nickel for everytime you typed "gutted header"