My specs are: Kinetix HF cats and Top Speed headers and stock cat back. I installed cats and headers at the same time, so I don't know who the culprit is unfortunately. But I do know that at stock I didn't have a rattle.

Now, when I accelerate in 2/3rd gear around 2500-4000 RPM I get a tin rattle noise. Goes away past 4k rpm. It's ugly. I heard an M3 once take off it had the same noise. Is something loose? Normal? Who do you think is the culprit?

 

sounds like rasp

I have the same setup - on a warm-day I get a slight rasp on the 1-2, 2-3 around 2-2.5K RPM, but it disappears after 2-3minutes of driving.

 

maybe ur heat sheild is rattling

 

heat shields have to come off or else the headers won't fit.

 

rattle is jst a rattle and rasp is that noise that jst makes you want to put your hands over your ears..........so you tell us, or take a video and we'll tell you

 

Are you getting married soon? Could be a couple of tin cans tied up in the back of you ride... (maybe you're girl giving you a hint) J/K

 

its the high flo cats. i get it too @ 3k - 3.5k seems like ithe rattling is going away now after 2 weeks. it sounded like it was hitting heat shield at first but now it doesnt do it as much, but still..... if i slowly rev up it doesnt make the sound , but if i floor it , sounds like rattling of tin cans.

 

killerlexus you're right if you slowly accerlate (rev) it will not rattle....it's only when i get on the gas hard. I will try to take a sound clip. There is no heat shield cause as atlantic knows those are removed.

It's ugly and annoying! I asked my mechanic and he says it is the HF cats too. He also said I should have gotten test delete pipes to remove the sound. I wonder do all HF cats rattle like this? Or just kinetix.

 

No experience with the Kinetix, but I don't have a rattle with my Crawford cats.

 

If your getting a rattle from CATS, then the core has disconnected or broken...no other reason.

It should not be this way - ever. If you are getting a harmonic rattle from somewhere else, different story. You'll have to get the car in the air and rev it to see if you can really pinpoint the noise source. You can use a long screwdriver or breaker bar held to your ear and to different sources to find point the noise as well as pushing against object to see if it goes away.

Rick

 

i have that rasp or rattle too, it's from the thinned walled alphawerks headers. thats what mrc told me. i'm used to it now. lol

 

Thanks Rick, I am not sure myself if it is the cats - I guess the only way is to get it up and see like u say. My mechanic was also guessing too. It may well be TopSpeed headers. Interesting about the thin walled comment - so there are headers out there with different thicknesses? Is that why crawford costs an arm and a leg

 

There are few differences in headers. You either have equal length, I call them spaghetti headers, or you have some sort of other shorty style, pretzel headers.

The real functionality difference is equal length will give you the best top end speed and HP. The shorty style will be for most of us street race ands 1/4 mile guys and gals.

Quality speaks for itself in the flanges - thickness and weld quality. Are the welds inside the flanges or outside - inside is best - but are there stress relieving welds on the outside as well? Those are VERY important details.

Quality speaks to mandrel bent pipes and size of pipe, not crushed bends to hammered areas as well. Welds should be clean as well.

Quality speaks to the collector. Is it stainless or welded inside, etc.

Quality speaks to the coating, polished or not, etc.

Headers on our cars are not great performance enhancers unless you wildly modify the car for NA or go with a SC. Otherwise they are sound enhancers, that cost a pretty penny. They will cost you TQ and give you minimal HP at BEST - but the sound is awesome!!!

So, be wary of what you buy and why. Companies like Strup and DC Sport for under $500 for ceramic coated versions are there and sell mass quantities for a reason.

Rick

 

Rick, other than Crawford, what headers for the quality metrics you just mentioned would you recommend?

 

I installed race pipes with a stock exhaust on my sedan and all kinds of "tinny" rattles showed up. Here's what was happening... The pipes were unobstructed to the flex pipe causing it to balloon. The threads were bouncing off each other as air was escaping. I could only hear it at 3000-4000 rpms. It sounded horrible. I have sine removed them until I get my cat back installed. I rattling from the exhaust tips. There were more but I couldn't isolate them and I figured I'd just wait until the cat-back came in. I would guess that the HF cats would present the same problems for you, though I'm not sure if all Gs have a flex section. Bottom line, I think you're free flowing more than your stock cat-back exhaust can handle.