Gutting the standard cats

[whitecliffs]

Hi just picked up a charlie chan exhaust of ebay for £160.00 result.
ive got some headers too and was thinking of gutting the standard cats,as i cannot seem to find any cat bypass pipes, ive heard this will throw the cel light but ive also read that by fitting long lambda sensor bosses this will aluminate the problem.
Any thoughts on this and has anyone done it or iam i better just fitting the headers,exhaust and leaving the cats alone.
Ive a 1.7 turbo diesel van which i gutted the cat and it made a big improvement allowing the engine to rev more freely but thats on a turbo
regards steve

[j.fro]

If you're going to gut the cats you'll need to reflash the computer to prevent the CEL. The long lambda sensor bosses won't do it. Doing all of this, you'll pick up top end power, but you'll lose some low end torque.

[whitecliffs]

thats what i thought dont really want to go down that route of remapping the ecu
done that before with motorbikes just an endless spend of cash.
will leave the cats alone and enjoy the sound.

[Bigsmoothlee]

Theres nothing to lose and everything to gain in terms of power when you delete the cats in a boxster. The front Cats are too close to the engine, and the rear cats are at a funny angle.

Last friday, I installed ebay headers, gutted the cats at the mid section, and added a NHP exhaust. No loss of torque anywhere. Feels like I gained between 10-15 hp ( Im running a 911 3.4 engine )

Heres the trick with the rear cats. They're not easy to gut. They're made of foil, and its EXTREMELY difficult to remove all the material. It took me 3 hours per a side, and thats with all the tools in my shop ( Torch, air chisel, long needle nose pliers ).

And, in addition to that, the exhaust gases echo and make a strange sound in the empty cat, so I am going to remove them and install a pipe instead.

Oh, and if you dont flash the ECU to ROW specs, you'll get a CEL. Ive read that Subaru guys install spacers to their rear o2s with a cat delete, and that BMW guys install O2 simulators. So there are 3 options to avoid a CEL

[whitecliffs]

iam in the UK so my car only has the two rear cats and ROW specs ECU exhaust and header will be here thursday so got a few days to think which route to take

[Tim1137]

Originally Posted by Bigsmoothlee

Theres nothing to lose and everything to gain in terms of power when you delete the cats in a boxster. The front Cats are too close to the engine, and the rear cats are at a funny angle.

Last friday, I installed ebay headers, gutted the cats at the mid section, and added a NHP exhaust. No loss of torque anywhere. Feels like I gained between 10-15 hp ( Im running a 911 3.4 engine )

Heres the trick with the rear cats. They're not easy to gut. They're made of foil, and its EXTREMELY difficult to remove all the material. It took me 3 hours per a side, and thats with all the tools in my shop ( Torch, air chisel, long needle nose pliers ).

And, in addition to that, the exhaust gases echo and make a strange sound in the empty cat, so I am going to remove them and install a pipe instead.

Oh, and if you dont flash the ECU to ROW specs, you'll get a CEL. Ive read that Subaru guys install spacers to their rear o2s with a cat delete, and that BMW guys install O2 simulators. So there are 3 options to avoid a CEL

You installed those like 200 dollar ebay headers right? How did you like them? I was looking at them today. Hows the fitment and does it make the exhaust sound raspy?

[Bigsmoothlee]

Originally Posted by Tim1137

You installed those like 200 dollar ebay headers right? How did you like them? I was looking at them today. Hows the fitment and does it make the exhaust sound raspy?

I installed the $139 ebay headers. I could not believe they fit so well. I was prepared to have to do some cutting, bending, and modifying to make it fit, but it fit right in place.

Here is what I did:
Loosened muffler
Loosened center pipes
Loosened the headers
Finger tighten header bolts
Tighten 3 bolt flange
Tighten headers
Tighten muffler clamps

The fit was very close, and I couldnt install the flange gasket without prying the header and center pipes away from each other without a pry bar.

I imagine that if you were to just bolt the headers on and tighten them in without loosening anything else up, you would have an issue with fitment. But be prepared to heat all the bolts up with a acetylene oxygen and torch...or nothing will come loose without breaking.

The sound is amazing, very raspy when you accelerate, quiet at cruising speed. A lot of this depends on the silencing properties of the muffler, I chose NHP because it was supposedly mild.

And by the way, Im sure with fabspeed you'll pick up a few more horsepower than you would with Ebay headers...but there is no way in hell im paying $1700 for short headers. If someone offered an intricate, equal length runner design like the Euro spec BMW M3, I'd understand...but come on, these are only 2-3' at most!

[whitecliffs]

Originally Posted by Tim1137

You installed those like 200 dollar ebay headers right? How did you like them? I was looking at them today. Hows the fitment and does it make the exhaust sound raspy?

i found a US ebay seller doing them for 99.00 bucks on saturday.
here is the item number 230653008020
comes with gaskets bargin

[Tim1137]

Originally Posted by whitecliffs

i found a US ebay seller doing them for 99.00 bucks on saturday.
here is the item number 230653008020
comes with gaskets bargin

how was fitment?

[Bigsmoothlee]

No problems with fitment here

[whitecliffs]

Originally Posted by Tim1137

how was fitment?

i didn't get them was just looking got mine from the UK

[Tim1137]

Im thinking about installing a set of the ebay headers and keeping the OEM exhaust muffler and the secondary cats. Im just trying to get a little more sound out of the exhaust without spending all the money on a system.

what are my options for keeping the CEL off for the cat codes?

[whitecliffs]

Originally Posted by Tim1137

Im thinking about installing a set of the ebay headers and keeping the OEM exhaust muffler and the secondary cats. Im just trying to get a little more sound out of the exhaust without spending all the money on a system.

what are my options for keeping the CEL off for the cat codes?

Near me theres 1/4 miles ish tunnel once ive fitted the headers and exhaust will do a video at 6500rpm through it....lol

[whitecliffs]

ok removed my exhaust system this morning only 3 bolts snapped on the header but soon removed them with an extractor.
Porsche should be ashamed of them headers look like there off a tractor.

Didn't know this until this morning my car is only fitted with 2 lambda sensors at the front.

So if i gut the cat its not going to bring on the cel light...or is someone going to tell me it will?

[Tim1137]

Originally Posted by whitecliffs

ok removed my exhaust system this morning only 3 bolts snapped on the header but soon removed them with an extractor.
Porsche should be ashamed of them headers look like there off a tractor.

Didn't know this until this morning my car is only fitted with 2 lambda sensors at the front.

So if i gut the cat its not going to bring on the cel light...or is someone going to tell me it will?

gutting the cats in the manifold will, gutting the rear cats will not.

Im scared to remove my manifolds i dont want to break a bolt in the engine

[blue2000s]

Originally Posted by whitecliffs

ok removed my exhaust system this morning only 3 bolts snapped on the header but soon removed them with an extractor.
Porsche should be ashamed of them headers look like there off a tractor.

Didn't know this until this morning my car is only fitted with 2 lambda sensors at the front.

So if i gut the cat its not going to bring on the cel light...or is someone going to tell me it will?

You're on a RoW car. There will be no CEL on your car for catalytic converter reasons what so ever. You could run with no cats at all and not get a CEL. Only North American cars have cat health O2 sensors.

[whitecliffs]

Originally Posted by Tim1137

gutting the cats in the manifold will, gutting the rear cats will not.

Im scared to remove my manifolds i dont want to break a bolt in the engine

my car only has the cats at the rear but as from tomorrow she will be catless

as for the bolts thats the risk but if you have the means to repair then you'll be ok
i heated mine up 1st but if i had heated up the ones that snapped a little more i reckon they would have come out

[whitecliffs]

Originally Posted by blue2000s

You're on a RoW car. There will be no CEL on your car for catalytic converter reasons what so ever. You could run with no cats at all and not get a CEL. Only North American cars have cat health O2 sensors.

cheers for that cat-less tomorrow

[berty987]

You may want to look at the article posted on planet-9 ref gutting standard cats, and the performance gain. Though the article is based on the 987 , the principle is the same on a 986. Personally I would buy a performance manifold without cats rather than gut the 986 standard units as the manifolds are so cheap. 987 manifolds are still very high priced , even for catless ones. If you gut standard cats you have the issue of a less than optimum gas flow , which will reduce power mid range. Lambda probe extenders may not work , but maxspeed offer ones with built in mini cats which appear to work very well.

987 Gen 1 - All Models Manifold / Header De Cat - Articles

[whitecliffs]

Originally Posted by berty987

You may want to look at the article posted on planet-9 ref gutting standard cats, and the performance gain. Though the article is based on the 987 , the principle is the same on a 986. Personally I would buy a performance manifold without cats rather than gut the 986 standard units as the manifolds are so cheap. 987 manifolds are still very high priced , even for catless ones. If you gut standard cats you have the issue of a less than optimum gas flow , which will reduce power mid range. Lambda probe extenders may not work , but maxspeed offer ones with built in mini cats which appear to work very well.

987 Gen 1 - All Models Manifold / Header De Cat - Articles

ive got a 986 which had the cat-less manifolds and just the rear cats also it only has the front lambda sensors,ive got new performance manifolds and back box,
with having only the front lambda sensors gutting the cats shouldn't bring on the cel light