I am considering removing the catalytic converter from my S. I was wondering if anyone has done this and what the outcome may be. I have just ordered the HKS Hyper exhaust and I started thinking about the entire exhaust system. There are a lot of ponies stuck in that thing. I consulted my very knowledgable mechanic and my performance magician and they both think that the car will still pass admissions standards in NY. Long and the short of it I was wondering if anyone had attempted this and whether it had a positive or negative effect on the over all driving experience.
By the way I understand that this is not the best way to preserve mother nature and I will only leave the car this way IF the car passes the dyno exam when we do a test run, so please leave the Green Peace hat on the rack.
Thanks

 

Please for give any mispelled words. I forgot to spell check.
Thanks

 

Actually there isn't much hidden ponies even with cat. removed.
There are few members including myself tried this.
Shaner and I probably have gone extreme on the exaust side with very little result.
I had single exit Amuse exaust with HKS racing header, Back Yard Special straight pipe, and round off with Mugen ECU.
Removing cat was the last step and difference was too little to justify.
I probably gained 1-3 hp at best and turned it into a gas guzzler.
If you can tweak the ECU maybe, but for now it seems pointless.

I also believe you can pass the emission with the cat off.

If you want to try Back Yard Special straight pipe, you can have mine for $175.
Construction is first rate and it is beautiful.



I don't recommend running cat-less with stock ECU.
Tim Ham of MG racing is only one who has done this for a bit but you don't want to do that.

 

little gains as noted, do yourself and the environment a favor and keep it on & avoid a fine.

about ten years ago, in Houston, the cops knew what to look for on mustangs and camaros - instant impoundment (if that's a word) and $2,300.00 fines. Of course, it was a typical car out there on the road and they knew where to pick them up at. I doubt any cop these days would fine you and take your car away just like that, but it has happened.

 

At first glance at the subject I was thinking this was "Off Topic"
Shows how much I'm mechanically inclined...

 

Plus, the exhaust smell + bad carbon staining on the exhaust tips... I had the car up to change the oil and put the catalyst on while I was under there. I thought it would give me a few extra HP with the SC but it just didn't...

Keep it on!

 

I run mine w/o a cat mainly because of my turbo (have full 3" exhaust) and unless you have an sim to fool your ECU your check engine light will stay on and you won't achieve any kind of performance gain.

 

I have the Mugen ECU which removes the second O2 sensor from the engine programming... and I still receive no cat-less performance gains.

I am looking forward to dyno-ing the car with the cat back on...

 

As derryck have mentioned running catless with stock ecu spell disastor. When I took down the Mugen ECU for sale I didn't remove the straight pipe with it. I kept it on for a day or two and sure enough it would trigger check engine light and the car started to run like crap(hesitation, no vtec, etc).
But the oddest thing is that Tim Ham actually ran fine with stock ecu and catless. Of course it triggered the check engine light but he didn't seem to have any problem.
This was at the Asheville meet and observing his car going all out, it seemed fine. Odd indeed....
I guess, you may experience some problem at the beginning but it will stabilize again with some time?

I am going to ask Tim about this.

 

Thanks for the feed back. After reading your replies I have decided to leave the cat in place. I was considering the removal for more power and the increase in sound, but if there is a chance of poor performance (especially no VTEC ) then I would rather leave well enough alone. Thanks again. Now I can't wait for my exhaust to show up so I can start setting off some car alarms.