When to replace main cat?
 

So, when is it prudent to replace the main cat? I've heard horror stories of this thing getting clogged and lighting a car on fire. I'm not really in the mood for such a thing, and my car is looking at around 103k miles on it (well, on most of the car, not the engine :) ). Also, if I replace the cat with a hi-flow, would that count toward the exhaust mods even if I don't have a catback yet (as it pertains to tuning a PFC)?

What's a stock cat cost vs. a hi-flow? Anyone have any comments on either of them and the various brands that might be available?

If you need a new cat, I would suggest going ahead and getting a High-Flo. Yes that would count towards your air flow for needed an upgraded/replacement ECU. The High-Flo will of course open up your car to more air flow thus needing more fuel.

I didn't see an open intake so I'm assuming you are still using the stock intake with not modifications to it. If that's the case, you'll be fine with adding the high-flo cat and not upgrading your ECU.

Depends on who you talk to as to when you need to upgrade the ECU. Pettit, M2 and other places that offer replacement chips usually have them programmed to work with basic mods (like intake, dp, high-flo cat, cb).

It was put to me like this when I started modifying my car, I asked the guy about it and he asked me this:

"Do you like your car?"

I said, "yes"

"Do you want to have your engine rebuilt?"

I said, "nope"

"Upgrade the ECU'

;)

I'm currently running the Bonez High-Flo Cat and like it a lot:

http://www.rx7.com/cgi-local/3catalog.cgi?cat=4&part=1

Hey Mahjik, how's the rest of your exhaust set up? And do you have emissions testing in Kansas City? I was just curious if someone could pass in our cars with a DP, Bonez cat, CB, and functional airpump. Also, do you have the PFC?

-Scott

So, the real question here is, at what point do cats usually clog up and catch your ride on fire? I'd like to avoid that if at all possible, so if anyone has any anecdotal numbers that I can use for reference that'd be great.

And, yes, your observation was accurate, I have no intake or exhaust mods other than a DP.

Right now I'm running the Bonez Downpipe, Bonez High-Flo cats and a GReddy Power Extreme cat-back.

I'm still waiting for my Pettit ECU to get here (:( ). I know they just moved, but I would like to get the ECU and other stuff I ordered installed before winter...

I have not had an emissions test on the car since adding these components. We have them every other year here so this is not my year, but I've read messages of people passing emissions with similar setups in California. So I don't think I'll have a problem passing here. ;)

As far as a clogged cat causing the car to catch fire? I've never heard of that. Usually the clogged cat on an RX-7 just causes low boost since it will restrict the air flow. However, if nothing can pass through the cat, I'm sure it could overheat the engine and possible cause something to ignite. You should see a significant decrease in boost WAY before that though...

High flow
 

Just replaced my stock Catalytic converter with N-Tech because it's comb filter was loose inside, making a rattling noise. Feels as if I've gained 20-30HP, awesome. Go for it, you'll wish that you should've done it sooner.

Goddamn though...$800 for a cat? Man, I can't handle that right now. I think I'll sit tight for a bit before I do anything else to the car. Besides, I'm off to the track in a few weeks to learn how to drive this puppy like it was meant to be.

Naw, that link that I posted was for the full exhaust replacement, so Downpipe and High-Flo cat.

High-Flo cats usually run anywhere from $300-500 new. If you don't care about new, you can pick them up used cheaper.

But you have the right idea. Don't just buy something cheap. If you can't afford what you want now, wait until you can.

Re: High flow
 

How many miles were on your original??

when u do get that Hi- flow- let us know --- im in the same boat as you are.

Clogged Cat
 

A lot of the horror stories told about main cat clogging are because of parts of the pre-cat coming loose and therefore clogging the main cat. Thats why its so important to get a down pipe to reduce your risk of clogging the main cat and saving the rest of your engine and turbo life.

post in the parts wanted/selling section of the forum (at the bottom) saying that you want a hi flow cat and you should get some responses. I did and it saved me about $200:D