lsb

Hi,

Does anyone have any experience of fitting a cat bypass pipe ? I am looking for a little more noise from inside the car and a small increase in power would be a bonus...

At this point I do not want to fit new headers or a full system as the car has only covered 3500 miles.

Would fitting such a pipe cause "check engine" warning lights or require an ecu remap ?? Any experiences, costs and suppliers would be appreciated. Here in the UK exhaust system upgrades to the Black don't seem to exist, so to save on a custom made solution I'm hoping a bolt on part may be already available.

Thanks.

jrcart

I deleted the cats all together on my BS, however I have done cat "passthroughs" or "dummy cats" on other vehicles in the past. A cat "passthrough" pipe will pass a visual inspection since it maintains the out cat housing and make it appear as if a cat is still in place. Not being all that familar with the AMG I can tell you how I did it on other cars in the past, here are the tools you will need. A hammer, rubber mallet and a long thick screw driver or steel rod. After removing the cat from the car drive the steel rod into the honeycomb material with hammer or mallet until it starts to break apart, continue until all of the material is removed and the cat housing is hollow, use air or water to blow out the small pieces. Next find a good shop to open up the flanges (or weld on new flanges) on the stock cat and insert a peice of straight tube through the cat, weld and reinstall on vehicle, and like that you have bypassed the cats. You might have to play around with relocating the sensors or you may get some CEL flashed on your dash, this should be easy for they shop to do as well. I have used this method on an M3 and a CTS-V and some of my Pony cars when I was younger. If your state does a visual inspection during emmisions testing this is really the only way to go.

Also note our cars have secondary cats/resonators, if it is just a little more rumble you desire you might want to start by removing these, they are not emissions required in most places and should raise the decible levels a bit.

Obviouslyt he right way to do it is with an entire new set of exhaust, as I mentioned mine completely eliminated the primary cats, I only have a set of small resonators just to keep it sounding not overly obnoxious.

_AMG_

Renntech makes "sound pipes" which replaces your 2ndary cats. Its pretty expensive, around $2440 but i have seen people buy this on a Black Series.

LZH

Just remove the secondary cats and you will get the desired effect - louder at WOT with lots of pops and barks when you get off throttle.

user z478747

I have Renntech headers and soundpipes (secondary cat bypass) on my BS. I first mounted the soundpipes, did a video and then installed the headers and did another video.

http://www.youtube.com/watch?v=akW30NuKdiw

Here's a cleaner vid of start up with headers/pipes

http://www.youtube.com/watch?v=aAvoJZR-W0k

LZH

Chuck - are those the stock exhaust tips ??

user z478747

They are the stock tips.

lsb

Thanks for the replies chaps. The secondary cat delete pipe seems to be just what I am looking for. The Renntech "sound pipe" doesn't come cheap though

Chuck, thanks for posting the videos - very helpful. Did you (or anyone else) run the sound pipe as a standalone upgrade ?

Was the increase in sound noticable from inside the car ?

In your opinion was it worth $2.5 k, as upgrades go ?

Was there much cutting required to fit the pipe and can the secondary cat be refitted easily if needed ?

Is the Renntech pipe THE one to have or are there alternatives ?

Sorry for all of the questions, just trying to gain a little knowledge through your experiences....

jrcart

You ask is the $2.5k worth it? I guess that depends on how badly you want louder exhuast, I can tell you that that $2.5k will not buy you any hp as where a cat delete or cat bypass as I described will be much less expensive and will gain you several hp and give you an increased and impoved exhaust note.

LZH

Just have your 2ndary cats cut out and straight pipes welded in their place. Below is a thread I started about mine, with a video and writeup. I think it's what your looking for and is less than $500. Good luck:

https://mbworld.org/forums/w211-amg/...ghlight=delete

alcpimpin

I just had a guy straight up cut the secondary cat out and put in place a straight pipe welded on.. At first it was clamped... No problems with the engine lights. Sounds awesome; especially under a tunnel

lsb

Thanks again for the replies chaps.

JR - My car will need an MOT (inspection including emissions test) next year so taking out the cats completely will likely make the car fail the test but thanks for taking the time on the info on how to remove the inside of the cat

I think the secondary cat delete sounds like the way forward. Thanks LZH for retrieving your earlier thread, great noise !!!

bill ewo

Does the Renntech or Evosport set up still pass smog (headers plus sound pipe)? Was reading the threads (not all 20 pages) and it seems that most prefer the Evosport over Renntech.

LZH

No - Evosport setup will not pass smog in CA without CATS.