SleeperX

Very good point I think I might leave my secondary cats alone in order to prevent a CEL. If I replace the secondary cats with racing cats, I think it could increase the risk of getting the check engine light. As Chiromikey mentioned earlier, I think the true bottle neck is the location of the primary cats.

E55 RUSS

YOU just need ot located O2 sensors as close a possible to Secondary Cats !!!

https://mbworld.org/forums/w211-amg/160072-removed-primary-cats-got-ses-lights.html

Be careful with O2 sesors and you should be fine...


Mike...

Have actually dynoed you car after you installed full exhaust system, what was your benefits ???

What diameteris your X-pipe, do you think it makes any power...I am starting to think or making X-pipe as well but keep th rest of exhaust stock ??? or I better do everything including the rest till the mufflers ???

Been told many times by Vadim and Cory and VRUS that E55 Exhaust is perfect and doesn need to changed, changing to diff config can only change SOUND and in the worst case loose power...

ProjectC55

Yep!

SleeperX

I assume that replacing the resonator with an X-pipe is what will create the extra hp because I don't think the resonator is restrictive at all. Have you seem Supersprint's X-pipe resonator.
http://www.supersprintna.com/product...arch_model/221

ProjectC55

Not tru. Replace the secondary cats with high flow units and move the O2 sensors and you'll be good to go. They will definitely reach the operating temp it needs in order not to trip the CEL. I've had no CEL problems. And Chiro is correct. Get rid of the heavy *** reso also and replace them with the stainless steel Vibrant reso's. RCT can get them for you,let Jules speak to Reinhart since they're friends . He charged me 90.00 bux when I could have gotten them for almost 20.00 cheaper. Remember don't put aanything else but stainless steel parts on your AMG exhaust(cats,reso's,pipes), great advice from Alfee and this is what MB uses stck.
4000 lb car will definitely benefit from whatever weight loss you give it. That's why we pull things like the spare tire,jack,seats and whatever we need to get the best 1/4 mile times at the track. To decrease weight.

E55 RUSS

O2 sensors need HEAT !!! If there is enough HEAT from 400 cell Cats, then there more then enough HEAT from 200 Cell CATS...

It will work...proper installation and wiring is the KEY !!!

SleeperX

Ok. I think you guys have convinced me.. No cutting corners. Drop in a new exhaust system from headers back. I think I would like to pre and post dyno my car to see the benefits. As well as take it to the track. This is going to be interesting. I am predicting 5-10 extra rwhp above simply gutting out my cats and maybe .1 decrease in ETs from the extra hp and weight savings. Anyone on this board tested this yet?

ProjectC55

That is exactly what I'm saying. If the O2 sensors don't reach a certain temp,(car running too rich or def sensor) the CEL light will come on.

E55 RUSS

That would be intresting... I wanna see you results...but cut Rpimary Cats first and see gain you had and then the rest of exhaust and dyno again to see if gained or loose power...

SleeperX

Yes.. I think that is the best way to test the system. Eliminate primary cats.. and then dyno.. install new exhaust system.. and then dyno again..
How much more hp and how much quicker in the 1/4 mile do you think it will be?

bfnnrgn

That and weight, I think I read the stock resonator weighs like 70lbs or something crazy like that. I'd replace it with this, much much lighter.

http://www.supersprintna.com/product...arch_model/302

AMG Rider

Frank..thats the setup that i have on mine....some say u lose low-end, but top-end is definately better...r u thinkin about removing ur resonator too?

SleeperX

Just had a conversation with Brandon at Kleemann. He mentioned something to me that I was unware of. Not only do we need to be concerned about the check engine light to pass inspection but we should also be concerned about OBDII readiness probing. It seems that some states only do OBDII readiness probing. By simply moving the distance of your O2 sensors you can trigger an OBDII readiness fault without triggering a CEL and you will FAIL INSPECTION.
Brandon is extremely knowledgeable and I highly recommend speaking to him before doing any exhaust work.

SleeperX

No. I will probably keep my resonator in the stock location although I hear it is pretty heavy.

blackbenzz

Dammit guys, stop making me spend money!

Chiro, your setup is SICK!

SleeperX

+1.. Do you guys know how much money you have cost me

E55 RUSS

You will definately feel more snap with PRIMARY Cats removed but I doubt thaat you would make any more power with the rest of the exhausts....

SleeperX

that is what I am thinking as well. Modding anything from the cats back I think we yield minimal performance enhancement.

My second dilemna is that I have renntech headers. Similiar to Evosport headers, these headers connect to the stock downpipes which is 47mm wide. These downpipes connect to the primary cats, and it isn't until after the primary cats that the piping expands to 70 or 74mm. Hence the bottleneck isnt just the primary cats. It is also the 47mm piping from my headers to the cats. How do I solve this issue without getting new headers?

blackbenzz

Why dont you guys just delete the primary cat and get an electronic cutout after the secondary to bipass the rest of the exhaust. Go back to quiet with the switch of a button. Electronic cutout is less than $300

SleeperX

I dont think this will increase horsepower, only noise..

chiromikey

EXACTLY...however, full blown cel's are still a problem. i relocated my o2 sensors right behind the new cats (you can see the bungs on the pics i provided) but i still threw a cel and had to have kleemann turn it off the via ecu programming. maybe it's a coin toss as to whether you'll get a cel or not but it's a definite possibility. this is all the more reason everyone modding should have a good data logger. bring it with you and double check and erase any possible fault codes right before emissions testing.

the resonator is heavy but not anywhere near 70lbs...probably more like 25. i don't see any reason to replace the resonator with supersprints overpriced version or their overpriced x-pipe. a good fabricator can make a better one or get a burns unit. an x-pipe should merge gasses into a tight area, forcing the gasses to increase their velocity, and spit them back out the other side to aid in scavenging. an x-pipe resonator will NOT perform that task. imho, the only thing nice about ss's products are the fact that they're pretty...something which you'll never enjoy after you get them installed.

blackbenzz

But you are bypassing the the resonator and mufflers = less restriction. I am by no means an exhuast expert, just shooting out ideas.

chiromikey

this is one of the reasons i'm not a fan of all the headers that bolt to oem exhaust. there's obviously a gain over the stock manifolds but it's a compromise. regardless, you should still see most of the gain by freeing the exhaust from the headers back.

chiromikey

sleeper's right...i've never seen an application where the electronic cutouts have made hp, just noise. that could be because they're almost exclusively bolted on a system that wasn't tuned to run open headers but that's still my experience.

bfnnrgn

Ha ha ha, I called a local shop to see if they would install what I wanted. Underdrive pulleys, cats, xpipe. They said nah, that's not a good idea, here buy these kleemann headers instead...