i just installed the high flow cats by kinetix on my z which already has the greddy evo II exhaust. during installation i relized that the new cats dont have the bracket like my race pipes did connected to them. therefore you have to take off the transmission braket like im sure those of you with the same cats know. hears my problem, since i have the evo exhaust which also takes out one of the stock brackets makes there be no hangers after the headers all the way to the y-pipe. this makes there not be enough support in the exhaust and i get a bad rattle now. it seems to be coming from a couple of places, one being the evap box. and another seems to be coming from the left cat. im guessing when the engine revs or shifts it puts torque on the exhaust and it bumps and rattles on the frame and evap box. does anyone have the same combination of exhaust and cats? i really need some feedback please, thanks in advance and sorry for the bad phrasing.

 

Yes, anytime you go straight pipe, you typically loose that tranny mounting bracket piece. The RT cats had those arms, but my straight pipes dont. I am getting a bit of a rattle from the factory cross brace, just forward of the differential. Crawl under your car and you'll know what I am refering to. The exhuast pipe runs above this brace, and on bumps, it drops down and rattles against it. What I did to solve the problem is put some heat wrap around the portion of the pipe that was rubbing.

You can also try loosening up your flanges on both sides of the brace, and the pushing the pipe up a bit, then tightening the flanges again. This could give you more clearance.

 

Hey,

I have the exact same set up as you and I also have a faint rattle/buzz when the revs are going back down say around 2500rpms to 1500rpms. I just had it checked today and the tech thought it might be the Y-pipe but, I've had the same noise since I put on my Kinetix cats. I used to have the Borla true dual exhaust before putting on the Evo2 a week ago. It is an ongoing project to get rid of that noise so, I may put the stock cats back on. I'll let you know. If you find out what it is, please let me know. Good luck! Btw, how to you like the sound/power of the Evo2?

Nilo

 

i know exactly which crossmember you are talking about and i put some shims between it and the pipe. now that part is fixed but it still hits somewhere else. i know the evap bax is one place for sure but it sounds like it is coming from another also.



yeah i know what busing sound you are talking about. it is just the high flow cats. it was louder with my test pipes than it is now. it is the so called "rasp" that everyone talks about. but with these cats you only hear it on the fall of a rev not during regular driving.

 

yeah, even the EVOII on my G35 is rattling on that crossmember - I just put two 1/4" washers to space it out a little more, but it stil rattles slightly when I shift into reverse, and from reverse into drive... I think I'll try the heat wrap on the pipes - thanks, GQ...

 

im so pissed off right now. i fixed the rattle from the evap box with some shims but the terrible rattle is coming from the cats still. i looked under the car the best i could with a jack and everywhere is fine now(crossmember, evap box) except for where the actual cats are. when i looked up there, there is only about a few mm between the cat and body of the car. whenever i accelerate i get the worst vibration and rattle and it gets quicker as the rpms get higher. so i know it is the cats hitting the body but i dont know how to fix it.

 

I just installed my kinetix cats last week and have the EXACT same issue. i was told that the cats rub against the heat shield under the car. a friend told me to use a hammer or something and make the gap between the cats and heat shield bigger. which would push the heat shield up towards the body of the car. gonna do that this weekend, will let you know how it turns out. this seems to be ANOTHER problem with a kinetix product.

 

yah thats exactly what it looks like to me. so now i guess i have to take them off to do the job. thanks man. let me know

 

That "buzz" sound everybody is talking about I have it too. It was a lot worse with the Helix test pipes but it's still noticiable with the kinetix catz. As the car warms up it seems to go away. As for the rattles, it's most likely the heat shield next to the cats, I removed mine on both sides and it got a lot better. I barely hear anything right now and the funny part is that I can just hear leaving home early morning when the car is cold, as soon as it warms up it goes away, for me it's something inside the cats that makes that noise. For all of you with the "rattles" try removing the heat shield on both sides near the cats.

 

you could try wielding something in place or get some of that spray foam stuff at a hardware store that will fix it for sho' i use that stuff all the time go to a hardware store and ask them for spray foam insulator in a can and they will knolw what you are talking aboout

 

Thats not very safe. Foam on super hot cats....think about it.

 

i bent away the heat shield a bit but it still rattles when the engine torques hard. so im gonna try some insulated heat wrap around the cats and see if it works like that dynomat stuff people use for subwoofers. if it doesn't i guess i have to do the hard thing and take the cats back off and take out the shield.

 

I don't know if you really need to take off the cats to take the heat shields. Well, I did mine while replacing the cats so I'm not sure about that but try it first cause the heat shield is a small piece with 3 bolts only.

 

For what it is worth, I had no rubbing or rattling when I had the RT Cats but since I replaced those with the CrawFord Cats early this week, I get the rattle from the left cat against the heat shield as there is barely any clearance between these two parts. My installer bent the heat shield away from the Cat and that minimized the rattle but it is there when I give it 75+% gas from a dead stop. I haven't heard it other than then. The installer told me it is dangerous to take the heat-shield out since the heat from the Cat will go through the floor of the car and at a minimum will be felt in the inside. I'm supposed to go back on Monday to take them off, bend the heat shield / body to get ride of the rattle.

On a side note, the Crawford cats IMHO crap all over the RT ones. They sound almost stock but the power is definitely there. With the RT Cats, the power used to come on strong at around 4K rpm but before then it felt as if I was losing power slightly while with the C.Cats, the power is there throughout the RPM range and there isn't that dramatic power surge at 4K rpm as before. I talked with the RT rep and he said they are having problems with the RT Cats only with the VQ3.5 and he's blaming our engines/ECU for miss-reading the exhaust flow and adjusting the fuel wrongly which he is attributing to the much higher than usual failure rate of their Cats with this engine. To each his own but I do like the sleeper sound but slightly throatier. I guess time will tell how they are going to hold up.

 

I don't feel any heat coming from the cats and had exposed my car to high temperatures. You should be fine taking off the heat shield

 

I'm taking my car to a shop this afternoon to have this problem fixed. gonna cost me $150 but i wont have that damn rattling anymore. this guy sees this all the time with the kinetix cats and explained to me why it does that, even gave me a brief hand schematic...lol. the cats have good sound & performance but the design is all wrong. will let you guys know what was done and how it turned out later tonight.

 

i think im gonna get some headers soon then im gonna just dismantle my whole exhaust system and wrap everything(headers, cats, cat-back) and remove the heat shields then. it will be one big job and then i'll be set with never having to go to the exhaust system agan.

 

Hmmm... I've got KINETIX high-flows and they do have brackets on them to mount to that center support bar.

Is KINETIX making them without those brackets now? I don't get it.

 

Yes. They were having fitment issues with the brackets so they removed them.

 

First off, the desing on the cats is not 100% correct. Obviously the design doesnt leave enough space between the cat and the heat shield. Another problem is that the flanges on the cats arent welded right (has clockwise/counter-clockwise twist). when they are bolted up to the exhaust is causes the exhaust pipes to twist. Look at the exhaust from back-to-front or vice versa (car may need to be on lift to see it). You will notice that the exhaust pipes have shifted (one may be lower than the other). after bangin the heat shield in to give the upper portion of the cats room, the flanges on the exhaust were loosened and the exhaust was repositioned. This gave proper space between the frame in the middle of the car, and space between the sway bar and pipe (was also rubbing). if you do not have TD then sway bar may not be an issue. Now i have NO RATTLE WHAT SO EVER!! . Cost me $120 but it was money well spent. Big ups to the guys down at Speed Force Racing in San Diego. If you are a Z/G owner in SD then SFR is where you wanna go!