I'm tired of the compromise between power and a smelly exhaust. Test pipes were awesome for power and response on my JWT TT. 30-40wrhp.

But the car stank up my clothes and everything else it came around. Not good if you have to meet business clients like me or if you just dont want your car to stink.

So I install the Ultimate Racing cats and no more smell but it feels like someone stuck a potato in my exhaust. Ok not that bad but I could really feel a loss in power and response.

I dont think the commercialy available HFC are made for turbo guys. I think we need bigger diameters and less cells for reduced back pressure.

This is what I'm thinking. Downpipe to a 3.5" then a universal 3.5" 200 cell psi spun metal catalytic converter. You think this would do the trick? Or use a 100 cell ?

Here are some universals I found searching Google. Metal'cat so far seems to be the best and makes up to a 3.5" cat.

http://www.metalcat.com.au/

http://www.jetex.co.uk/website/sport...p&dia=3.0+inch

I'll be the guinea pig if any fabricators or exhaust companies want to work something out. I'll post before and after dynos and maybe someone could start selling these.

 

IDK, maybe just a proper tune would take care of the smell with the test pipes. My exhaust doesn't noticably smell worse without cats

 

I was tuned after the test pipes were installed and my AFR was 11.5 to 12 through the rpm band. Still stunk.

 

Like I said, I never had an issue with my exhaust smell. the only times you really smell your exhaust is when you come to a stop sign/light or are sitting at an idle. At those times, you may need your tune adjusted. AFRS at WOT mean nothing in regards to what we are talking about here. I don't claim to know a whole lot about tuning, but 11.5+ AFRs are bit lean from the knowledge I have

 

I'm using the split second that comes with the JWT TT. I think the only area I can tune is under boost. The car should act like stock at idle. I would think lean would smell less?

Still, for those that chose to use high flow cats commercially available direct fit cats are 2.5" at best and use 300 to 400 cell per inch substrate.

I want to use 3.5" and 100 to 200 cell per inch. So an inch more volume with a third of the resistance.

 

the larger 3.5" shoudl be a huge improvement

 

Also, I think all of these direct fit HFC are designed to bolt to stock headers (2.25"?) So this creates resistance even before the cat substrate. A turbo downpipe is (3" to 3.5"?) and the exhaust is hottest and has the most volume. Squeezing that into a 2.25" hole and then through 300 to 400psi catalytic converter substrate has got to hurt turbo performance.

 

Very true....

This is very subjective; how bad a car's exhaust smells, but honestly I wouldn't even consider running cats on my TT setup. Never has anyone commented on the exhaust fumes on my car. When I see threads like this, I must think that because I am a farmer and smell stinky *** diesel fumes most every day, maybe I just don't notice my car?? I usually find the cars that stink the most are stockish N/A cars running test pipes.

I don't drive my car for business, but if I did, I wouldn't worry about driving anyone around in it, including potential clients. It most definitely doesn't stink up my clothes.

I say good luck to you, hope the big cats work out for you

 

Thanks Zivman,


Is this a job for a local exhaust shop? Or should I get a fabricator who knows the 350z?

 

Any capable shop should be able to handle this - just take it to a shop you trust

 

It's a known fact that the more free flowing your exhaust is on a turbo, the more boost and performance you'll get. Taking a 3" downpipe and choking it to 2 1/2", would reduce flow and therefore reduce boost and power.

Give Tony a call at Fast Intentions. You want to get 3" or 3.5" Metallic CATS for FI.

www.fastintentions.com

 

I've been trying to get the Metal 'Cats for a WHILE, .... i can't ever get a good response from the U.S. distributer, ... and now I get no reply from the AU guys..... i was pointed in different directions and never got a company to actually sell me the 3" versions! A bit frustrating to say the least!

Tim at SFR will make me some as soon as I get a 3" Metal Cat, ... i just need to find a place to purchase as well.....

 

I hope you are able to get these made. I would like to see the results

 

Have you tried this guy?

http://myworld.ebay.com/ebaymotors/carshopinc/

I'll call him tomorrow.

 

Call Tony at Fast Intentions....

 

Hey John, Do you know the JWT TT downpipe diameter?

 

sorry, not off the top of my head.

 

I'll give him a call.... I just didnt see 200 cell cats on his website. To me this is as important as the diameter of piping. If you increase diameter and reduce resistance I think you can get something that will flow close to testpipes.

 

Absolutely and I agree. Not everythig they can get is on the site though...he can get 150 cell cats too...

Rick

 

If 200 cell per inch cats pass the sniff test and work with the latest obd2 requirements whats the point in 300 and 400 cell per inch cats? Performance wise?