DEE-AMG

Hello All,

I am considering taking the two rear cats off my exhaust system. But having some doubt?

Was at a Mercedes specialist today, he advised, not to take the rear cats off my car. Reason being, it would cause the front cats to work extremely harder. Also he said the Lamber sensors at the front would be giving wrong readings to the rear sensors and would throw up the engine management light. Long term, he said it is not a good idea.

I am booking my car into an exhaust garage to have the following done.


Take rear two cats off. (unsure yet)
straight pipe into (magnaflow) x pipe or a custom H pipe?
change the two mufflers for 6 x 3 oval silencers. (I think the smaller the mufflers, the better the sound?)
staggered quad 4 x 3" tips.

All advice and help much appreciated.

bhvrdr

I would think that removing the back cats would actually cause a reduction in backpressure and corresponding exhaust gas temperatures if anything causing the two remaining cats less wear and tear. In addition, your primary lambda's are for measuring o2. They are pre-cat. The secondary lambda are for monitoring cat performance. They do not change mixture control. They will simply throw a code but no affect on performance should occur.

cheers! mike

MBRedux

Don't...

DEE-AMG

deciding to not bother touching the cats at all until they are worn and need changing.

as for the mufflers/silcencers. am i right in saying, the smaller the box the better sound quality?

bhvrdr

Not necessarily. Sound quality is also subjective. I'd choose a muffler with a sound you will like from reviewing/listening to others who have already used them. I'd also choose one that uses straight through cores for the best performance. Companies like magnaflow use these high performance designs and also provide the industry standard lifetime warranty.

cheers! mike

DEE-AMG

I want the car to have a nice loud grumble when stationary.

Once I put my foot down, would like it too scream but with as little rasp as possible.

I did intend to go full straight but worried the rasp will sound too much and also don't want it sounding cheap and jap racer style.

jimmythegreek

The size of the mufflers dont necessarily change the tone to a good sound. Its the chambering that controls the tone. If you get rid of the resonator and add decent mufflers it will sound great. No need to remove secondary cats, if it was an 8 cyl and u were doing full exhaust including headers yes pull cats. In our applications theres no need, and doing so causes lots of probs