High flow cat (HFC) question
09-07-2018, 03:08 PM
#21
^^ +1 
09-08-2018, 08:34 AM
#22
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
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
09-15-2018, 10:37 AM
#23
So I replaced my cat with a 63mm HFC because the core of my stock cat had become loose and begun to rattle at idle and i am in an Emissions state.
The car didn't become any louder, however the sound with stock exhaust sounds more refined. Not sure how to explain it other than the high notes sounds more "full" and less "muffled" by the second core of the stock cat.
.
The car didn't become any louder, however the sound with stock exhaust sounds more refined. Not sure how to explain it other than the high notes sounds more "full" and less "muffled" by the second core of the stock cat.
.
09-16-2018, 08:54 AM
#24
I have two S2000's. Both later model DBW.
One with intake, big bore throttle body, 70mm TP, dual Spectrum Elite exhaust, and FP tune. Delivers great mid range acceleration. Transforms the car and driving experience.
The other is a relatively stock car with a 63mm Berk HFC. Had to change as OEM Cat was broken and OEM is too expensive as replacement.
To get full gains in a tuned car - a HFC/TP and exhaust is a must! The stock car with the HFC has no power benefit except if you install a FP unit in it. Plus it adds a slight resonance sound which some may not enjoy.
FP basic map for intake and HFC still lets you lower VTEC. Also either turn off secondary O2 sensors through FP so P0420 CEL is not triggered or install sensor spacer/extender with HFC (important note to pass emissions).
One with intake, big bore throttle body, 70mm TP, dual Spectrum Elite exhaust, and FP tune. Delivers great mid range acceleration. Transforms the car and driving experience.
The other is a relatively stock car with a 63mm Berk HFC. Had to change as OEM Cat was broken and OEM is too expensive as replacement.
To get full gains in a tuned car - a HFC/TP and exhaust is a must! The stock car with the HFC has no power benefit except if you install a FP unit in it. Plus it adds a slight resonance sound which some may not enjoy.
FP basic map for intake and HFC still lets you lower VTEC. Also either turn off secondary O2 sensors through FP so P0420 CEL is not triggered or install sensor spacer/extender with HFC (important note to pass emissions).
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