They will all sound roughly the same. The exhaust will have a greater impact on the resonance of the exhaust system as a whole than just the cats.

But it is a big misconception about the HFC's all being roughly the same. There are a lot of manufacturers that are taking your run of the mill replacement catalytic converter and calling it a "high flow cat". Chestobo just published some results from one of these other so called 07 350Z "high flow" cats. They performed just barely above the factory 2007 units.

The results were skewed in favor of the Technosquare HFC's that he was testing against, but the data itself was very useful and much appreciated.

After studying the factory cats and how Nissan braced them we've decided that they do need the same support tabs that the stock cats have. That support tab just needs to be properly gusseted. Lighter or not, the cats need a support tab. That's why you now see the majority of test pipes with support tabs as well. Test pipes are a hell of a lot lighter than any HFC, yet they still need support tabs.

Fast Intentions is able to get away with not using support tabs on their HFC's because they are using an angled outlet cat. The stresses of the engine twist are placed on the top side of the cat vs. the inside radius of the bend on the pipe. That radius is taken up by the top of the angled cat. (Edit: But, you can still crack through the cat itself, despite the weld holding up. Just saw a set of FI HFC's today that were cracked through).

If anyone who orders our product and you want another pre-cat wideband bung & plug then send me an extra $20 and I'd be happy to weld another one in there.

You are correct as of last Wed. All HFC's (03-06 & 07-up) will have our fully gusseted support tabs. During the 1st part of 2008 only the 2007's had our support tabs.

The engine is trying to push the cat down, while the exhaust is trying to hold it up. The cat will try to bow downwards. The support brace holds the cat up and transfers those stresses to the tranny instead of the exhaust & cat.

Hope that helps!

Cheers,
Bryan

 

^^
Interesting.

I'm looking to buy your HFC for my 07. Still on the fence about it though.

 

great info...thanks

 

I have Crawford cats right now and have had them on the car for a little over a year. From what I understand, they are just "gutted" stock cats. Not really sure what that means entirely. Needless to say, I should've done more research as I not that thrilled with them. I will be buying Berks shortly.

 

So the Berks just makes the nismo exhaust sound louder and does not change or take away from the nismo? i love the sound of the nismo. Also, how will the hfc be on emissions testing, will there be a problem passing? It seems like an hfc/test pipe is the next best n/a mod on a revup after a spacer/mrev2, just making sure that is true.

 

^^ +1

Also, can berk clarify about the positioning of the second bung for the aftermarket wideband O2 sensor.

 

Just make sure the WB O2 bung is upsteam of the cat or the AFRs will be inaccurate. Ie. Too lean.

 

That seem's like a bit of a doodoo if berk put the WB O2 bung after the cat then.

 

If you want a pre-cat bung on there then just send me an extra $20 and we'll TIG one in there for you.

 

I had Berk HFC's with my Nismo and let me put it this way. Before the HFC's, i thought the nismo sounded perfect and was weary of installing HFC's to change the sound. Afterwards, i didn't regret it one bit. Do you love the sound if your nismo but wish sometimes it was a bit louder? That's exactly what the berk HFC's will do for you. Louder, but not too loud. You should still pass emissions with Berk HFC's.

 

Bryan, I am interested in getting your HFCs for my '06 to mate them to my Nismo C/B. Would you please PM me your shipped price to 80108?

 

If I got HFCs (Berks are the top of my list), how much would sound increase when at cruising speeds (30 & 60-70MPH)? My Borla TD is flawless in this regard, and I want to retain that quietness in the lower RPMs as much as I can if I get HFCs - which is why test pipes are totally out of the question for me.

So, how drastic will the sound increase be?

 

same to 18324, got any military discounts? Lol, doesn't hurt to ask

 

I dont' know about with a Borla, however, with my Nismo after the car has warmed up, you could barely notice it durring idle and cruising. Durring acceleration the sound is definately present, but not obnoxious.

 

I agree. Although the nismo is a lot louder after getting HFCs.. it's not annoying farting loud like i've seen with MANY setups with either Test pipes or HFCs. I just dislike my slight rasp at 2800-3000rpms under warmup.. (first 5-10mins) after, i can run it as hard as I want and not a hint of rasp. Warm-up is louder too, but all Z people know that the car runs very rich and at higher rpms to cause those sounds. BTW i have some soundclips of NISMO and HFC posted already under the HR forum.. just not that great of a vid. Will make another one soon..

 

so if the o2 bung is needed anyways...why make it an extra charge? i don't get why it isn't just an automatic thing? to be more specific...the placement of the bung....if it is to be pre cat or not...why not have it like the stock set up?

 

Has anyone seen the JVT racing cats? The price seems right but nobody has installed them so Im a little reluctant to get them just yet.

 

They're talking about the WB o2 (for tuning purposes).

 

any of you guys know why Berk decided to add a brace to their HFC? Is it because they found problems with their original HFC? Im one of many of the members here who have bought the HFC before the brace was put on

 

are your HFC's still holding up fine after all these months? yes. so NPF (no problem found).

It's all about making your products better, constant improvement over here. Any product in the world can be made better, weather it be car parts, TV's, or laundry soap. Once you stop improving, that's when you start to fall behind. Take a look at what's happened to Ford & GM over the years. And now take a look at Toyota, Nissan, & Honda. You never want to be that guy....

Hope that helps...