In Europe, the only available hfc is from Tegiwa, and it is 70mm, 200cell.
(I know there is a Berk 63mm in USA but shipping and import duties are high to Europe).

Here on the forum i've read that pairing a 70mm hfc/tp is not a good idea with the Oem exhaust (60/63mm) because of the bottle neck effect.

However, I sent Tegiwa - who sell the hfc - a message and they said its not a problem to use their 70mm hfc with the oem exhaust (or any 60/63mm exhaust).

Should I trust them, or should I not install the 70mm on stock size exhaust?

I don't want to lose any power! Hfc is for soundpurpose only. Have driven both oem cat and tp. Hfc is alternative.

Ps. Car is stock, no tune. Engine will not be tuned in the future.

Please your opinions! Even better first hand experience

 

They are correct, its not a 'problem', you just won't make as much power! It will certainly all bolt up, which is all they care about. That and making money from a sale!

It has been proven to lose power. Has this vendor done any dyno testing with the stock exhaust? What do they have to lose by lying about it to make a sale?

 

https://www.s2ki.com/forums/uk-irela...-99-a-1005808/
Have Berk 63 HFC on mine and in UK
give the above a looksie

 

Do you think I will lose power compared to the stock cat? Or compared to a tp? I honestly didnt feel any clear improvement with the tp on oem exhaust, perhaps at the top rpm. Definitely nothing noticeable at the bottom.

 

thanks! its an old thread but sent them a msg.

with which exhaust are you running the berk hfc? Can you tell me what happened with the sound of your exhaust compared to the stock cat? Thanks!

 

I'd personally not put a high flow cat on the car for "sound." Not worth it. The 63.5mm version is on my car in front of a Tanabe Medalion Turing exhaust to improve exhaust flow and allow the VTEC engagement point to be set to 3600 rpm which greatly increases mid-range torque as well as roughly 10% more power at redline for the setup.

Opinions and internet sound clips are dangerous to your wallet as everyone's opinion of "not much louder than stock" is highly subjective. Example: A buddy and I put Berk 63.5mm high flow cats and Invidia Q300 exhausts on both our cars based on notes on this forum and we both pulled the Q300 exhusts in a couple of weeks as they were deafening -- his wife resorted to ear plugs! Our new systems test at 95dBA about 2 feet from the exhaust tips with a calibrated sound meter. No ear plugs needed. Since you're interested in sound, not performance, here's a gratuitous but not particularly useful Youtube exhaust video with just the Medalion Touring exhaust and the stock cat.


Find someone local with the exhaust or cat you're considering and ride inside for a while. Note there are few drone-free aftermarket exhausts.

-- Chuck

 

How does this HFC and exhaust setup allow for a lower VTEC engagement point?

 

My guess is that a 70mm HFC would be less bad than the stock cat, but it's probably worth the extra money to get a 63mm HFC instead.
With stock cat optimal VTEC point is probably around 5000rpm, HFC flows much better which is why you can lower it to under 4k.
But you still need something to alter the factory tune, like flashpro or an aftermarket ecu for example.

 

thanks for your input. Unfortunately there are no s2k's around here. Ive had a q300 and was quit pleased only the low bass tones on rpm drop to stationairy at the redlight (with cat) annoyed a bit. A tespipe solved this issue, but we ditched the exaust for i dont remeber. Later tried the titan tips and it sounded really different. Dunno why. Was removed as well.

for now looking for that racecar sound (that tp gives) but at a lower sound level. Stock cat way too quiet and muffles the sound. Similar to your video. Hence I thought a hfc might do the job to go somewhere in between cat and tp. For that reason looking for info

 

Here is a uk dealer that has the 63mm Berk listed https://www.tarmacsportz.co.uk/berk-...-flow-cat.html
I'm sure there are other sources here in Europe though