High-Flow Cats Discussion - HFC
 

Hello all,

I am wondering why people buy HFC or Test pipes. When dealing with the smell of unburnt fuel, CEL, and emission testing... It seems about $600 for 5hp... correct me if i'm wrong, but it seems like $$ could be better spent.

...or is it just a matter of getting every last drop of HP from the car. I thought a Cat-Back exhaust pretty much got all the gains that could be had via exhaust.

VOTE IF YOU READ THIS

Thanks all,
:tup:

The cats are most restrictive part of the whole exhaust system.

But dollar-to-dyno... doesn't seem worth it??

I like TP's for many reason. I'm more of the hard core enthusiast first of all. But TP's for me are cheaper, lighter, more flowing, great sound (IMO), love the smell of raw fumes, and I don't have emissions.

In addition to the benefit of opening up the air flow, the sound is also more aggressive sounding and for me that was what I wanted. I have no issues with the smell of fumes. Never had a problem passing emissions, since no CELs are on it. Here they won't sniff test it unless you show having thrown a CEL(s).

Berk HFC's and ARK CBE's. No raw fuel smell and sounds good too.

I felt the most gains when I installed the ART pipes. Well worth it IMO.

:driving: :)

Oh come ON... 200 views and only 24 votes :eek:

Jon, do you have test pipes? Your exhaust sounds awesome.

It also plays a big role if you are FI or NA:tiphat:

Oh really. Hehe

:icon23::roflpuke2:

I'm stationed over In KY/TN and have my car registered in TN where they don't do emissions. Do any of you know if VA has emission tests? (sniff, visual, or w/e) Thanks.

I did all the standard bolt-on (intake, CBE, HFCs) mods prior to going FI. The HFCs were by far the best (most gains) of the bolt-on mods.

When people post "but its only 5hp", you're missing the point.

Modifications are synergistic. They all work together. Sure JUST HFC's might yield 5whp (just guessing) but when you add other components, they all work together to make the most power.

Any one particular part might not be a great bang for the buck, but when you start adding them together, thats where you get the benefits.

I can guarantee that adding HFC's to an already existing free flowing 3" cat-back exhaust system is going to yield noticeably more power than doing "just HFCs".

I'm pretty sure high flow cats have dyno'd much higher than just just 5whp whether it is 8whp or 15whp or somewhere in between, opening up the biggest restriction in the exhaust is going to produce nice gains under the powerband and improve driveability.

I have AAM HFCs enroute. Will be installed on our 2010 7AT w/ our pre-existing OEM Nismo takeoff catback.

Looking for increased performance and volume.

I put on my Z1 HFCs ($375 ish shipped). More power, no CEL.

people do these mods for two main reasons IMO

sounds good

fun to do

nobody thinks there car is going to make a large jump in performance by bolting a particular pipe on

I have HFC's and a cat back. That along with a Stillen Gen III air intake and my car came alive. It sounds good and runs better. Very noticeably faster. It wasn't that much more in the grand total of the exhaust so I just did it. I do have the SES light on right now though. Waiting a while for break-in so the computer re-learns the O2 readings and I'll have it cleared.

I beg to differ:
http://img.tapatalk.com/d/14/05/16/u8edene5.jpg

http://img.tapatalk.com/d/14/05/16/u6uqenap.jpg

Hold my beer...

i think in this case, that qualifies as a tank instead of a pipe

Do you gain hp with test pipes on fI? I'm thinking of going test pipes.

If you can get away with it/live with it, TP's are one of the BEST bang for the buck mods, A set off ebay will do the job (you will need one or two sets of defoulers -- ideally at a 90* angle -- for secondary O2's or a tune)

I recommend resonated ones as the unresonated ones will be extremely raspy.

Whether N/A or FI, they will net gains.

Now if you can't get away with it for various reasons, go with (resonated) HFC's.

If you have the $$$, N/A or S/C, LTH would be my recommendation for maximum gains, although if you need a cat in there, you'll have to get creative.

I would look into defoulers or a tune... if the secondary O2's are the cause, that SES is related to the degree of delay between primary and secondary voltage readings, interpreted as due to the presence or absence of a functioning cat. When the voltage readings are too close together in time, that implies failed or missing cat and eventually trips the SES. The defoulers are intended to slow down exhaust gas from reaching the 2ndary O2 too quickly.

My Berks HFC was installed on Friday and all I have to say is that this is the best bang for your buck. However I do have an issue with my check engine light coming on the following day but my mechanic did warn me in advance. If your looking for performance and don't want to break the bank, go for the berks hfc because it makes a big difference in performance and sound once you get past 4k rpm.

Anyone have any advice on the check engine light?

I know the SES light is difficult to predict, but I got the Z1 HFCs and have had zero issues. Good customer service as well.

Did you ever figure out your CEL issue? I have a 2011 Nismo that I plan on getting AAM HFC.

Did your AAM HFC ever throw a CEL?

I'm running AAM HFCs and catback exhaust. Ran with no CEL for about 8 months and then came on. AAM didn't have an explanation. Installed standoffs on the O2 sensors on the cats, reset the CEL and running fine ever since.