Gutting the standard cats - 986 Forum - The Community for Porsche Boxster & Cayman Owners

whitecliffs · 05-13-2012, 11:13 PM

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 · 05-14-2012, 04:40 AM

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 · 05-14-2012, 07:47 AM

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 · 05-14-2012, 08:54 AM

Quote:

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 · 05-14-2012, 09:12 AM

Quote:

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 · 05-14-2012, 09:20 AM

Quote:

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