Sixth.Gear

Hey all,

As of late I've been getting a pretty bad rattle at idle and right around 2600-2900 rpm. I finally narrowed it down after a lot of searching around the car and on the forums and found it was the cat. It seems to be the cat itself, and not the heatshield around it. After doing some more searching around the forums the general response was either go TP or HFC. I'd much rather go HFC so I don't have to deal with the stink of the exhaust, but I'm not sure which one to go for. Berk has two offerings, a 70mm or a 63.5mm version. Eventually much further down the line I'd like to get an aftermarket exhaust, but right now I'll be staying stock. Which size HFC should I go for? Thanks!

MR.T

It seems that used cats are readily available in this community. I just bought a 60k one for around 80$ or so. If you're not completely sure what your doing with exhaust yet, that might be a better, cheaper, temporary solution.

It'll give you time to do some ride arounds with other s2k owners and hone in on what exhaust you want. That's my plan at least.

If you do go this route, helms recommends replacing both gaskets on the cat, one for each side, and the spring bolts at the header to cat connection.

Can't help you on the hfc/tp sizes though, sorry.

RacerXI

Either 63.5mm or 70mm will work with a stock exhaust. While a 70mm flowing into a stock cat back isn't ideal, it'll still work. The best flow would be achieved by having matched exhaust sizes throughout your exhaust. A used cat is always an option and i'm sure you could sell your stock cat to a scrap yard.

Carbon Blue

you better get that CAT changed out ASAP, the media inside will blow out and cut the o2 sensor clean off which will cost you a hundred plus dollars to fix and a check engine light.

Froth.

Whatever you do, don't attempt to Gut a factory S2000 converter unless you want a real good workout as the substrate inside is not a ceramic based 300cell design but rather a spiraled metal wire core 200cell. These are EXTREMELY difficult to Gut just because of the nature of the design, you cannot simply "Punch" out the internals, they must be Drilled/Pressed/Cut/Pounded out.

For what it's worth though, it works.
Happened to me, Mine never rattled but I guess eventually the first "Puck" of the converter slid backwards and snapped my Secondary O2 sensor off, throwing P0137 CEL. You could see it had slid back almost 1/2" over time and the indent of the O2 sensor was evident in the Catalyst material, it began to rattle terribly because the tip of the sensor was stuck between the two Catalyst pucks.

Sixth.Gear

Yikes, I read about the O2 sensor getting sliced off but I didn't realize how expensive those damn sensors are! Looks like I'll be getting the 70mm high flow cat because eventually I'd like to get the T1R 70R-EM catback.

I'm guessing I could go throw it up on a lift and remove the O2 sensor to see if the media on the inside is really the culprit and then proceed from there. The sensors don't have a special gasket that need to be replaced if removed, correct?

Saki GT

The OEM cat is a HFC, and if you are still under warranty (100k mi I believe), just have the dealer replace it for free. The O2 sensor is likely already damaged, so it will need to be replaced as well, and should also be warrantied.

S2KIrishman

since when has honda had a 100k warranty? first ive heard of it...OP, chances are its not under warranty

Saki GT

Its not Honda, its Federal - 80k mi and 8 years on cats, lifetime on seatbelts. A Honda dealership will do the work under warranty in either case - I've had my S in for both.

S2KIrishman

interesting...so youre saying if i ever have issues with my seatbelts, honda has to fix it? i feel like the dealership would fight me on this