Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Recommended Posts

I know a lot of people send a lot of money buying straight pipes for the secondary cats to get that extra sound and HP. Has anyone ever removed the cats and just "rodded" it out. Meaning, chopping/bashing (hammer) the honeycomb core out with a metal conduit pipe until opened up. Then reinstall them and done! Should have same effect right?

Might be a $10 mod, max!

Link to comment
Share on other sites

  • Moderators

I know a lot of people send a lot of money buying straight pipes for the secondary cats to get that extra sound and HP. Has anyone ever removed the cats and just "rodded" it out. Meaning, chopping/bashing (hammer) the honeycomb core out with a metal conduit pipe until opened up. Then reinstall them and done! Should have same effect right?

Might be a $10 mod, max!

Before you start beating Hell out of your cats, I'd suggest finding out what a replacement would cost; might just change your thought train a bit................

Link to comment
Share on other sites

  • Moderators

I thought I might find on Ebay or someone that had already replaced them with aftermarkets and do it to them to see what happens. Clogged cats would work well. I was wondering more if anyone else has done it already?

With even used cats selling for hundreds, the aftermarket pipes are the more economic way to go............

Link to comment
Share on other sites

  • Moderators

This has been done on some AUDI cars, just google it

Just because something can be done, does not necessarily mean it should be done, or even makes economic sense. With scrap yards paying money for even dead cats, why would you want to destroy a perfectly good one?

Link to comment
Share on other sites

I guess for the same reason anyone would take theirs cats off and replace it with a straight pipe that cost close to $600. It's a cost saving question. I haven't heard anyone on this thread do it anyways. The difference between doing it and a straight pipe is the materials inside the pipe.

Link to comment
Share on other sites

  • Moderators

I guess for the same reason anyone would take theirs cats off and replace it with a straight pipe that cost close to $600. It's a cost saving question. I haven't heard anyone on this thread do it anyways. The difference between doing it and a straight pipe is the materials inside the pipe.

Check the market for used but serviceable cats for your car, it is probably close to the same number............... New cats are selling for north of $1600 each, a couple of used but serviceable cats for a 996 recently sold for about $750 from a salvage yard. You do the math.....................

Link to comment
Share on other sites

I did.

http://www.ebay.com/itm/04-PORSCHE-CAYENNE-TURBO-FRONT-EXHAUST-PIPE-7L5254450E-or-7L5254400A-OEM/271304958968?_trksid=p2045573.m2042&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D27%26meid%3D2939751651209938966%26pid%3D100033%26prg%3D1011%26rk%3D3%26rkt%3D4%26sd%3D261174241615%26

If you are removing them anyways for $600 straight pipes are you then selling the OE cats or are you keeping them to change back in case anyone needs them to pass an inspection? Do most people keep the cats for a "just in case" factor?

Link to comment
Share on other sites

  • Moderators

I did.

http://www.ebay.com/itm/04-PORSCHE-CAYENNE-TURBO-FRONT-EXHAUST-PIPE-7L5254450E-or-7L5254400A-OEM/271304958968?_trksid=p2045573.m2042&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D27%26meid%3D2939751651209938966%26pid%3D100033%26prg%3D1011%26rk%3D3%26rkt%3D4%26sd%3D261174241615%26

If you are removing them anyways for $600 straight pipes are you then selling the OE cats or are you keeping them to change back in case anyone needs them to pass an inspection? Do most people keep the cats for a "just in case" factor?

Some people retain the cats, some sell them. In many states, the vehicle will not pass inspection without the cats physically being present (yes, they actually look). Selling a cat-less vehicle is problematic as well, as some states place the onus on passing inspection on the seller of the car rather than the buyer; if it won't pass inspection, the seller has to either take the car back or fix it so it passes. I guess it all depends upon where you head is at. We only have a couple of customers running the pipes, they kept the cats to put back on when they sell the car.

At the end of the day, removing the cats really does not free up much power in anything short of a ten tenths prepared car (reflashed DME, full headers, etc.) regardless of what the cat bypass pipe sellers say, so taking them off a vehicle with no other mods really won't gain you much in performance, but could end up creating a lot of grief, including persistent MIL codes, inspection problems, sale problems, etc.... But it is your car, so you have to decide what you really want.

Link to comment
Share on other sites

The cats that are replaced are secondary cats. There are four cats in total on the Cayenne. The front pair are monitored by O2 sensors and are the only cats required for emissions. The rear pair serve as sound tuning and additional exhaust cleansing.

Replacing the rears will not void emissions or trigger a "fail" as they are not part of the active emissions system.

I had cat bypasses for a while but found the sound too raspy. I also looked at punching out the innards but that looked like a major PITA. The guts are ceramic, platinum and some other materials.

You will gain more in sound modification by replacing the rear muffler on installing bypass valves.

Link to comment
Share on other sites

I forgot to mention...... There were ZERO performance gains with this mod on my 2005 CS

On a normally aspirated vehicle, there are no gains to be had. If you have a turbo, then I can see some advantages where improved flow will yield more power.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.