for the more expierienced in this field.. which cat converters offer highest build quality, least rasp and best performance? I'm more concerned with having that fart canish rasp while accelerating, kills the Z expierience? I heard random technologis was a real good company from the search option.
Any comments??

 

RT's suck! If you search more you'll see many people have had them implode/collapse.

Most people seem to like Crawford H/F Cats. I love 'em, even more than my old RT's.

 

But i read you have to mod the crawford cats so they dont rattle and rasp? Is that true?

 

I love my Ultimate Racing High Flow Cats, great sound, performance and they look almost like stock

 

I heard:
- Random Technology cats have a history of blowing out
- Helix is very good (but would like more confirmation on this)
- Crawford is very good (but don't look as pretty as the 2-above)
- I haven't heard anything on Ultimate Racing cats
- Kinetix cats weld's aren't too great

I know helix comes with a heat shield too...I haven't looked into if the others do the same.

Again, just what I've heard...I'm thinking Helix may be MY choice when I do this.

 

+2 for Crawford. Workmanshipment and Fitment are excellent. As far as looks, they don't look like the stock cat, but they look like a stock cat, and could fool a visual inspector.

Lou

 

I think the highest quality would be the ones made by Nismo, I've not used them myself, but from the photos I've seen the look great and they also have metalic core instead of ceramic. But the price is a big negative. The only other metalic core cats are the ones made by Helix (and I think RT), but they don't look stock.

 

From what Ive heard , Crawford uses Carsound cats . You could have them made cheaper than what Crawford charges....If I would have known that , I would have had them made instead of buying the Crawfords . live and learn

 

Not sure where you heard that but I have the Helix high flows and they definitely don't come with heat shields and don't allow the use of the cat support brace like some cat and test pipes I have seen. I also removed my OEM heat shields when I installed them. With all that being said, I love them. They look great and sound great. Here is a clip of my car with the following installed:

Nismo Performance Cold Air Intake
Injen Super SES Straight Tip True Dual Exhaust
Helix High Flow Catalytic Converters
Altered Atmosphere Angled Plenum Spacer

http://350z.civichatch.com/exhaust.mpg (Right Click -> Save Target As...)

 

Ok thanks, i LOVE the sound of our car and it gurgles and it doesn't rasp Helix it is!...
Are there different versions of Helix cats? i.e. V4/V5 plenums.. v2 v1 Nismo CAI..anything like that?

 

i think they'll all have some rasp. i had kinetix; have ultimates. both rasp(ed).

 

Not that I know of. I got one of the first sets available from Gruppe-S at the beginning of the year so they might have changed the design later.

 

I'm sure the all have rasp, after all its just harmonic reonance amplified within the pipes, but w/ propper material usage, rasp is reduced and I just wanted to know which have the least amount of rasp.

 

My system produces no rasp. Crawford headers and cats, Invidia G200 dual system.

Lou

 

Heh, just gut your RT's and make them test pipes, works like a charm! Or even better by some disgruntled former RT cats owner's after they have already gutted them and reap the performance rewards!

 

I read that they have a heat shield here:
http://www.i-m-racing.com/he200cehica3.html

Then I saw some posts from someone who bought it saying he wanted to get it jet-hot coated but wondered if it mattered because it came with a heat shield.

Is this a new cat than what you have, or is the heat shield they are talking about just a heat-coating?

 

I have the Helix highflow cats as well. they do NOT come with heatshields, what you see is what you get. They were never offered with heatshield.

http://www.optionimports.com/ni35ing35.html

It was hitting the underbody when i first installed them, I had to bang the **** out of the metal to make it clear.

They do rasp with my stock y-pipe and stock exhaust, only when it's cold though.

overall, it's alright.

 

are there any cats available with a C.A.R.B. EO number? i dont wanna have to switch out my cats whenever testing/inspection time comes in CA... other than that, i think i would go with helix as well

 

If you visit a site that carries Helix and read the manufacturers specs it will mention that the canister itself is a double thermal shield. As for rasp, they DO rasp at least in my case. It comes on strong at over 4K rpm. They also made contact with the chassis and required a hammer to smooth out the offending chassis areas. So your mileage may vary.

 

Yeah you guys cleared it up. Here is what it says on that site:

Thermal boundary heat-shield for rapid light-off and maximum catalyst efficiency

That just means that the body of the cat holds the heat in better. What you see in the pic on that site is what you get. As for clearance, I also had issues when I first installed them with the driver side contacting the body. This was remedied by me adjusting my exhaust so that it wouldn't pull up the cat into the body. Overall I still think they are the best looking and performing high flow cats.