[cmitchell17]

Did anyone notice any sound difference, did it help quiet any of the exhaust leak and ticking noise that comes from headers?

I finally broke down and got a set of kooks 1-7/8, and I was very surprised how thin the stainless steel was especially at the collector.

The good news is, I know notice more cylinder airmass so at least I didn't throw $2000+ completely out the window haha. But now my car sounds like a old broken work truck or van with all kinds of exhaust leaks and rusty mufflers. I mean it honestly sounds horrible, but its what I expected from headers and removing the stock exhaust manifold. I know the factory uses pretty stout and thick cast iron, its also double walled (I am not sure if the factory does this for sound reduction or heat insulating for faster cat lightoff?, or maybe both?)

I feel like there has got to be a way to quiet down the crappy sounding noises, its especially bad at high loads and low rpms like when the engine is lugged down and the torque converter locked in low gear.

I feel like concentrating some kind of dampener or something around the collector area it would maybe help at least some of the noise. I really wish there was a aftermarket company that at least cared and offered a header that at least tried somewhat to mask all the crappy sounding noises.

[BruceWayne1LE]

Assuming you have thoroughly checked for leaks at the manifold gaskets and collectors. I would assume a high quality wrap would help insulate some sounds at the primaries. The TSP headers are some thick tubing. Kinda shocked Kooks would use such thin walled materiel.

[6spdhyperblue]

1. Seal the connections between the headers and the pipes at the flange with ultra copper rtv. Next time I might cut off those connectors and welding in quality flanges with clamps.

2. I like finding leaks on a cold start with your hands. The leaking hot exhaust will be felt puffing out of the spot before the pipes get hot

3. I do believe wrapping dampens the ringing of the tubes

4. Idk if ur dd tables are ramped up in cruise areas but taming that down and I think can help too. I would bet you’re getting more charge in the cylinder especially at low rpm. has the timing changed at all? adjust the knock sensors now with lts if you haven’t already. Iirc retarded timing can make it sound blatty.


Interested to see what you found for g/cyl. Did the idle become more stable now?

[cmitchell17]

Originally Posted by 6spdhyperblue

1. Seal the connections between the headers and the pipes at the flange with ultra copper rtv. Next time I might cut off those connectors and welding in quality flanges with clamps.

2. I like finding leaks on a cold start with your hands. The leaking hot exhaust will be felt puffing out of the spot before the pipes get hot

3. I do believe wrapping dampens the ringing of the tubes

4. Idk if ur dd tables are ramped up in cruise areas but taming that down and I think can help too. I would bet you’re getting more charge in the cylinder especially at low rpm. has the timing changed at all? adjust the knock sensors now with lts if you haven’t already. Iirc retarded timing can make it sound blatty.


Interested to see what you found for g/cyl. Did the idle become more stable now?

APC (airmass per cylinder) is up at peak (5800-5900rpms) from about .94 to about .97 so I am happy to report that volmetric efficiency is improved, but too bad I can't tell to what effect it is scavenging from the header primaries being optimal length or just decreased restriction from the stock cats. Also my "unofficial" 1/8 mile runs have decreased from 7.48@94 to 7.24@100, however the 7.24@100 was in 100 DA, most of the other ones at 7.5 were at around 1000 ft I think.

DD in the part throttle regions is stock, I have never had good luck trying to suit it to what I "perceive" to be better like decreasing it at throttle tip in for less jerking back and forth at low speeds. It just never responds the way I think it will, but I've never tried an analytical approach, just trying to adjust it by feel. I will say it does ramp up throttle position without downshifting to where its almost full load (low vacuum high map). This is when the header noise is at its worse and the crappy beat up work truck/van unrefined/broken exhaust sound.

I will admit, I do have a leak, I am getting a pending code for low voltage at bank 2 (I also had to cut an additional inch from what the Kooks instructions said to cut at 2-3/4" when I fit everything up on there at first, and it was still tight with the additional inch cut, and now the clamp has less straight length of stock exhaust pipe to clamp too). It eventually threw the code saying the fuel trims aren't responding, which I thought was off because the low voltage code is for bank 2 sensor 2 which is the post cat sensor and it shouldn't be trying to correct fuel trim feedback based on the #2 post cat sensor?

I hate putting on that exhaust sealant stuff since it gets really hard and makes a mess, even though I think it would work, which is surprising given how hard and prone to cracking it is.

Cruise and part throttle timing hasn't changed to my knowledge, but at WOT there is defiantly more knock and it occurs more frequently but only at WOT. Some WOT runs just have a little knock, others have a constant about .5-1 degree being pulled with very short spikes up to about 4 degrees.

I know cast iron is always the go to engineering material for sound dampening, but I am not sure if that's because cast materials are inherently thick to reduce cracking or if cast iron is just that special of a material. I can't see stainless being much different since cast iron and stainless should have relatively similar stiffness.

Its also amazing how with the headers and even with the cats, how much louder and how much more noise you can also hear from the muffler behind the back seat. I have tour mode commanded to close the NPP valves 100%, I think it might sound decent from the outside with them close, but inside it just sounds like a really high frequency rattle. This is not the NPP rattle, I had that and fixed it with the latest grinding the ear off fix.

I guess I could try some wrap and should be able to get under there and just wrap up the collectors, I think the collectors are the problem areas for sound radiation, if you look at the stock headers, the primary tubes on them aren't very thick, but at the collectors they have a thicker casted looking piece at each "Y" merge, however, the primary tubes on the stock manifold look like they are double walled, I know they are for a fact double walled in the downpipe at the primary cat.

[cmitchell17]

Originally Posted by BruceWayne1LE

Assuming you have thoroughly checked for leaks at the manifold gaskets and collectors. I would assume a high quality wrap would help insulate some sounds at the primaries. The TSP headers are some thick tubing. Kinda shocked Kooks would use such thin walled materiel.

How thick are the TSP headers? I wish I would have checked the Kooks before I installed them, I know Kooks claimed 16 gauge steel, not sure if that was just on the primary tubes or what.

[L78toLT1]

Gray cast iron is much better at absorbing the energy from vibration due to the flake like microstructure. High nodular iron is not as good at dampening vibration, but is much stronger. In steels, higher strength correlates with decreased dampening properties. The next time you're up to your elbows in a motor to the point where the crank is removed, rap on one of the counterweight with something metallic. If it's steel you will be rewarded with a sustained, high frequency ringing. If it's cast, all you'll get is a dull thud

[L78toLT1]

Originally Posted by L78toLT1

Gray cast iron is much better at absorbing the energy from vibration due to the flake like microstructure. High nodular iron is not as good at dampening vibration, but is much stronger. In steels, higher strength correlates with decreased dampening properties. The next time you're up to your elbows in a motor to the point where the crank is removed, rap on one of the counterweight with something metallic. If it's steel you will be rewarded with a sustained, high frequency ringing. If it's cast, all you'll get is a dull thud

This was in response to CMitchell's comment on cast iron. I forgot to quote the applicable section of his post.

[scantone]

I have the same headers and wrapped them. It cut the ticking sound down id guess half, but you still hear it when your at idle and cruising speeds

[6spdhyperblue]

Would a volant clamp seal that for you? They have the pipes butt up to each other. I won’t use the crush type again. If you’re not leaking at the header collector I’d say you’re in good shape, just fix that leak. I can never get those collector flanges to seal. It def broke my heart to use the ultra copper but the front o2s pick up the leaking they’ll wash down the cylinder walls! The trims go wild for a minor leak there.

[cmitchell17]

Originally Posted by L78toLT1

Gray cast iron is much better at absorbing the energy from vibration due to the flake like microstructure. High nodular iron is not as good at dampening vibration, but is much stronger. In steels, higher strength correlates with decreased dampening properties. The next time you're up to your elbows in a motor to the point where the crank is removed, rap on one of the counterweight with something metallic. If it's steel you will be rewarded with a sustained, high frequency ringing. If it's cast, all you'll get is a dull thud

Thanks for the info, how did they compensate for the decrease in dampening when they switched from gray iron in blocks to aluminum?

I wonder if there is any way to tell where the sound is coming from and weather it is being radiated from the collector outside steel or is something else vibrating? It's weird to me how much more noise comes from the muffler and from behind in the back seat now. I am assuming its just because now the stock cats are gone.

I believe sound gets best attenuated through either good mechanical dampening (like the gray iron you mentioned) and/or porous material, like foam, since the sound waves will hit the small air pockets and discontinuities. It's funny how sound is ordered (exists at a lower entropy) and to get rid of it, we can just "disorder" it. Like its extremely difficult and time consuming setting up a huge stack of dominoes, but all it takes is one little flick at the end and all that work is ruined fast. Yet it seems to difficult to get rid of unwanted noises, you would think they would be so fragile.

Makes me wonder if I could just put a bunch of sound deadening material up under the heat shields at the bottom of the car above the collectors?

[cmitchell17]

Originally Posted by scantone

I have the same headers and wrapped them. It cut the ticking sound down id guess half, but you still hear it when your at idle and cruising speeds

It may be placebo effect, but I think after fixing the leaks with the sealant, it has helped and now its a little quieter it seems? I have a high lift cam as well, so distinguishing the tick from the already present valvetrain sewing machine noise is difficult.

[cmitchell17]

Originally Posted by 6spdhyperblue

Would a volant clamp seal that for you? They have the pipes butt up to each other. I won’t use the crush type again. If you’re not leaking at the header collector I’d say you’re in good shape, just fix that leak. I can never get those collector flanges to seal. It def broke my heart to use the ultra copper but the front o2s pick up the leaking they’ll wash down the cylinder walls! The trims go wild for a minor leak there.

After fixing the leak with the sealant, I cleared the codes and took a highway drive (15+miles), so far no codes. However, there was still a history and pending P2097 (Post Catalyst Fuel Trim System Limit or something like that), but after driving home on the highway again, the P2097 won't come up again) so maybe I am good.

If this code does in fact go away, I will be decently pleased with the kooks and green cats being able to satisfy the emissions monitors. My main worry with getting these headers was that even with the cats it was still going to smell like unburnt fuel. So far as long as its warmed up I haven't been able to detect any strong smells. If I go put my face in front of the pipe when its running I can smell a little of that 2 stroke chainsaw, burning pungent smell but its not bad at all. I am also running E75 or so, but I have never noticed too much of a smell benefit running E85 with no cats versus regular gas.

The thinness of the collectors though and the fact that the clamping hardware kooks provides is totally ineffective have me really questioning the almost $2,500 price tag these have. I guess when something is not massed produced and completely made in the USA you definitely have to pay for it. I am almost tempted to buy a set of made in China speed engineering headers just because they are so reasonably priced just to compare.

I guess I need to hook up my wideband and see if I can do a little VE remapping, as the trims do look like they are higher now. Before I would usually never get about +/-5% but now I am seeing over 10%. I guess there is also the debate about if having longtubes effects the transient delay and timing given that the O2 sensor is farther away from the exhaust port now, but from what I have seen no one has been able to get a conclusive answer on if there is a better value we need for the proportional constants and stuff if we have headers to improve the feedback.

[jimadvig]

I got the Speed Engineering 1-7/8" headers and 3" catless x-pipes and all of the connections were to big and I knew going in they were going to leak like crazy. So I used copper RTV as well. But it didn't completely seal the connections up. So I ended up buying V-band clamps and welded them in at the header and the back of the H-pipe. Then welded the rest of the joints so I could at least remove the exhaust in pieces if needed. It seams that most of the slip fit systems leak. But I don't think TSP or Kooks are as bad as the Speed Engineering though. Those seam to have a tighter slip fits.

[cmitchell17]

Originally Posted by jimadvig

I got the Speed Engineering 1-7/8" headers and 3" catless x-pipes and all of the connections were to big and I knew going in they were going to leak like crazy. So I used copper RTV as well. But it didn't completely seal the connections up. So I ended up buying V-band clamps and welded them in at the header and the back of the H-pipe. Then welded the rest of the joints so I could at least remove the exhaust in pieces if needed. It seams that most of the slip fit systems leak. But I don't think TSP or Kooks are as bad as the Speed Engineering though. Those seam to have a tighter slip fits.

How bad is your undercar noise and engine lugging noise when inside?