FI HFC's - First Impressions
 

So I just installed my Fast Intentions HFC's (in 2.25" diameter, as per their suggestion w/ stock cat-back exhaust).

Install:
This install is very straight forward since it's just 5 bolts per side. The problem came when I saw that every bolt I needed to remove was completely rusted over. I'm not a big guy by any means, and would highly recommend you don't attempt this install unless your arms are 6" in diameter at a minimum. I had to get my buddy to crack the bolts for me, but then they came out just fine. Another issue is some of the angles you need to get in order to get at some of them. I had to use 2-3 bendy connectors to get at a couple of them on the header side.

The kit comes with all new hardware other than the gasket for the header side. They recommend you purchase some high temp silicone gasket stuff and use that. I don't know why they don't just include the gasket...?

After install:
When you start the car it sounds nearly identical to the stock setup. Once you get on the gas there's a largely noticeable difference in volume. The tone is exactly the same as stock, but a little bit louder. I actually was hoping it would be a little louder than it is. WOT is when you can really hear the difference and makes this mod completely worth the money / effort.

As far as power goes, I noticed a small gain in power mostly in the top end. I'm taking the G autocrossing tomorrow with them in so I'll have a better idea about power after that :driving:

Overall this is a great mod to get given the better exhaust volume, and the proven HP gains. Hopefully the butt-dyno will feel it after a more spirited run with it :D

great write up, have you noticed the infamous HFC hiss?

Not that I'm aware of. But great, now I'll have to listen for it :icon43:

i heard that the FI high flow cats are the only one/few that actually don't have a hiss

^ updates on the HFC's looking to getting some, does FI offer ceramic, metallic or both and which one would be the better choice? i want a bot of sound without any/minimal rasp.

I love mine, no hiss...

^ so no raspiness either?? and are they ceramic or metallic?? iv heard they offer both which would be better if you know? also any issues with CEL or smog? thanks!

Trav, the only guys who seem to have the hiss are the ones using stock exhaust with the HFC.

Honestly I don't remember... I think metallic. No cel issues or lights, I don't believe the HFC are smog legal, but I would double check with Tony

Ah, gotcha

I'm running a Gemini catback and FI HFC. I got the HFC hiss

Actually I wish that were the case.
I got the hiss from my Berk HFCs with Tanabe Medalion Exhaust.
Some guys blame this on the gaskets but all my gaskets were brand new.
In doing a lot of research it seems to be a by-product of most HFCs design.
It's not awful sounding but once you notice it for the 1st time it's an ever present sound on your mind.

Most quality HFCs won't throw any cel.
Thats mostly from test pipes.
A lot of guys down here in SoCal don't have any trouble passing smog with they're HFCs either.
Once again mostly from TPs.

The Hiss or Rasp is something that the 350Z/G35/G37/FX/370Z all do. You can look on any forum and when you take the stock cats off its going to be there. It just depends on the exhaust and how prominent it is.

I can say though with Turbo cars it does change and does dissapear. On my Z was the Greddy TT kit with AAM 3 inch DP and Greddy EvoTT 3 inch exhaust and there was absolutely no rasp.

Thanks a lot for all your responses guys, so the CEL is not an issue, now i will look more into the hissing that ppl are talking about, but is the sound annoying when you are not in a "spirited" driving mood??