I've been gawking at a lot of the cool stuff you have been doing since I picked up the Z for my wife on her Birthday in May.....thought I would return the favor.

Car Spec's:

2006 350 Z Roadster
6 speed

No engine/intake/exhaust modifications except K & N drop in filter


OEM Cat’s
Weight: 13.2 lbs.
Pipe I.D. inlet/outlet: 2”
Sound level – idle: 52 db
Sound level – 3,000 RPM: 80 db

Ultimate Racing Cat's
Weight: 6.0 lbs
Pipe I.D. inlet/outlet: 2 3/8"
Sound level – idle: 54 db
Sound level – 3,000 RPM: 88 db


Note: OEM Y pipe has 2” I.D. so a larger aftermarket replacement could free up flow even more.

Observations:In comparing OEM vs. UR sound levels, at idle they are very similar as the sound meter shows. As RPM increases the difference becomes more noticeable. I did notice the intake breathing sound with the UR cat’s that I did not notice with the OEM (maybe it is different or maybe it was there with the OEM and I didn’t notice).

Sound characteristics are similar on both setups. The HFCs have what I call the “Harley affect” where the engine has a much deeper tone at low and steady RPM under load. The HFC's have a deeper tone and are louder as the sound meter reflects. See what you think on the attached clips (not very easy to hear in the clips but more obvious "live").

The UR HFCs seemed to help throttle response and broaden the power band but these are subjective. The human tendency is to associate performance with sound and the facts sometimes prove this wrong.

Installation:
This car has 1,100 miles on it and has not (and will not) seen any rain. Getting the fasteners loosened on the header end of the OEM was a bear. I have a large assortment of tools so I had what I needed but getting the leverage to bust them loose lead to some bloodshed. Its pretty tight spacing on the header end. The outlet end was a piece of cake.

The quality of the Ultimate Racing cat’s looked good. Nice welds, smooth seems, stainless flanges and good fit/alignment with the OEM manifold and Y pipe. The UR also includes the mounting bracket just like the OEM cat’s which I think is a good idea. During installation, my only concern was the clearance (approx. 3/16” possibly less) on the LH cat near the floor of the car. I came real close to using a mallet to dent the floor a bit for clearance but I decided against it. Fortunately it does not make contact with the floor and there are no noises beyond the exhaust note. RH side has much more clearance.

The UR HFC’s had a bung on each cat for the O2 sensor, which I used. No errors or codes so compatibility appears to be good at this point.

Would I recommend?
Yes, if you like the OEM exhaust system but want a little more aggressive or louder sound levels. There seems to be a slight gain in performance but it could be the placebo affect. Although it is logical that it could help performance based on the larger diameter and less restrictive design.

Yes, if you're planning on adding an aftermarket exhaust at some point in time as the HFCs will reduce the restriction up stream of your free flowing exhaust and allow you to realize even more performance.

No of course if you are going the test pipe route or you want the branded bling of an aftermarket system.

No, if you are not interested in laying under your car for a few hours while donating some blood in the process. Sure you can pay somebody but it takes away the fun and sucks up funds that you could blow on other car stuff.

Would I do it again.....sure would.





http://video.google.com/videoplay?do...75791987188151
http://video.google.com/videoplay?do...35439919313464

 

nice write up

 

did i miss the clips?

 

....no, still working on uploading to site that I will link to. Files are huge (180 meg) so not sure if it will work. I suppose I can shorten them to reduce file size too.

 

dam where were u when i was in the 3rd grade and needed a book report... jk thanks for the tip how much are those high flow cats?

 

Bought them here:

http://z1auto.com/prodmore.asp?model...ust&prodid=580

$439 + $35 shipping which beats the hell out of most of the alternatives

 

180 mb???? holy hell...
No, but thanks for the write-up. I have contemplated this setup for a while now because I am not sure if I want to bite the bullet and spend a grand on a cat-back. Looking forward to the clips.

 

Great report. I have Test pipes in right now but i dont like the rasp so im going to HFC. With a 3" true dual, i can only wait to here its synphony!!

 

just added the video/audio clips to my original post....hard to tell the difference in the clips. HFC's measure louder on the sound meter but the clips don't seem to pick it up.

 

Wow, 3" TD, I hope you're gonna have a pair of very large turbos to go with that.

 

...really good post & info - Thanks

In the pic on the first post there's a screen on the HFC that I never noticed

- Is that the inlet or outlet we're looking at?
- anyone know it's purpose? (e.g flame arrester or is it to prevent particles from exiting the exhaust)
- how are they holding up?
- do any of the other aftermarket CATS have the same screen?

 

i have the UR cats and i love em. ill post sound clips of my setup/pics. Nice write up!

 

The "screen" is actually the catalyst. It is a honeycomb type material that is ceramic with a super alloy metal coating that flashes off (burns) remaining exhaust gasses to reduce pollution. Have you ever followed a 70's era car without the cat's? You get that strong, rich, unburnt fuel smell (cat's are just one of many components that reduce pollution). Installing TP's on a new Z will provide that same type of smell. I don't know about you, but I don't want my hi-tech, high HP Z to smell like a '74 Maverick.

The picture is shot from the inlet end.

They're holding up well but they have less that 1,000 miles on them as the car is a "Sunny Sunday driver" that would be driven more if the rain had better timing.

The OEM internals look very much like the Ultimate Racing in terms of the number or holes/channels. I guess I should have measured number of channels per square inch to get a real handle on it but I didn't. I'm thinking the HFCs get their higher flow rate from a shorter length catalyst. They may have a larger area too? .....speak up any exhaust experts.

As far as I know, all cat's have a similar design. The internal materials may differ slightly but the design is pretty constant.

 

thanks... I know exactly what you mean about eliminating the CATS. My '71 340 Wedge Plymouth is long gone

I like the design of the UR CATS and am now trying to confirm fitment on my G35 Coupe. Z1 Performace says 350Z only and they told me they don't know anything about the G35 ????

I messaged UR but have not yet heard back. No one on G35 Driver has responded yet with thier experience either.

What made you buy these and not the Crawford or AAM / Other Brands?

...long live sunny sunday drives!

LMG

 

Thanks for the write up. But will hi-flow cats pass emissions test? Any one have any problems with testing in SoCal with high flow cats?

 

350Z and G35 coupe cats are the same, even the cat back exhaust's are pretty much the same, with the G35 coupe versions being a couple inches longer. I know for the Nismo 350Z cat back exhaust, an extension is available to make it fit the G35 coupe. Hope that helps.

Gary

 

None of the high flow cats have an EO # or are CARB approved for our cars but, people have passed the sniffer test with them. If you are thinking of going with a set of aftermarket cats, please keep your stock versions in the event you do not pass SMOG test or a visual inspection as passing is not 100% guaranteed.

Gary

 

The channels per square inch you mention is the cell count. I'm not trying to steal your thread but, their is some very good technical info to be found at this Random Technology web page:

http://www.randomtechnology.com/technical.html

Hope that helps.

Gary

 

this fall will be 3 years and 40k miles with these on my car...nothing but smiles from the get go I mated it to an UR Y pipe at the same time, and it too, has worked out great.

I;ve gone through 2 inspections so far, not a single issue. They actually do not look aftermarket, which to me, was part of the appeal

Great write up by the way!

 

I have NISMO Headers and a full NISMO Cat Back Exhaust. Do you think UR HFC's would work with my set-up?