tw2

I figure more people have done headers here than the CLK55 forum but an M113 is an M113. I am considering having custom headers made, stainless long tube 4-1 with slip joins and ceramic coated inside and out. My local shop does an awesome warranty on leaking, cracks etc and has an excellent reputation. This will of course eliminate the primary cats.

- Are the secondary cats enough to stop the smell of gas with the primaries gone?

- Would these alterations with an otherwise completely stock exhaust be at all loud? Mainly I don't want to annoy the neighbors with cold starts as I live in a townhouse complex (in garage, door open).

- I presume a tune is required to get rid of the CEL? Are there any other options to get rid of it before having a tune done?

c32kompressor

the secondaries might be able to mask the smell but maybe not. I did shorties on my w209 55. they were good until they cracked but they were cheap. longtubes will be a bit louder than the shorties but not by much. it should be relatively quiet

amgen

I have Kleemanns mid/long-tubes.
Primary cats gone of course and the secondaries take very well care of
exhaustfumes in my countrys sniff-test. Actually they have said several
times my exhausts are very clean!

I´ve kept the rest of the exhaustsystem untouched, with a very nice
sound left. Not too loud. Tried for some time without the resonator but
it was far too loud for me, put it back on.

ECU-tune is a must to get all the power out of the headers, and to turn off
the CEL.

tw2

Thanks for the feedback, I won't bother with primaries then.

I found your topspeed thread again c32. I can't believe the stock headers have a 1.6" exit, thats 41mm for us metric people, insanely small. I would consider 2.25" barely adequate. Not that I know what is inside the resonators or mufflers but surely this must be by far the main restriction in the exhaust.

Good to know I won't wake up the neighborhood. I like to fly under the radar, at least near home.

c32kompressor

yup, the headers on the w209 55 and w203 55 and the main restriction.

amgen

Don´t forget primaries restrict a lot too.

c32kompressor

primarys are restrictive, not nearly as much as the stock headers

c32kompressor

while primarys are restrictive, they provide the necessary back pressure for our vehicles. this is where all our low end power comes from. cats really aren't restrictive anyway. they cant be too restrictive. if they were really as restrictive as people say, it would defeat the purpose of them. the combustion chamber temps would rise affecting emissions.

Naugamanator

With respect, I beg to differ on 'necessary back pressure'. Exhaust gas velocity at lower RPMs is what brings the low end power.

Myths about "back-pressure"
http://www.mustangevolution.com/forum/f312/t296628/

tw2

Good read. I learnt from previous cars that bigger is usually worse. Mild to moderate increase in sizing with a better design usually increases torque throughout most of the rev range. Otherwise it comes back to being a trade off and certainly low rpm torque is the most enjoyable for a daily driver around town.

Lenin

Absolutely agree. It's about the scavenging effect. just look up the exhaust design for a top fuel dragster. Very little backpressure considering the HP and TQ they generate.

C3Duece

IMHO you'd should replace the primaries with 300cell cats and ditch the secondaries completely. Cold starts with headers/high flow cats will be loud enough to wake the dead.

amgen

If you decide to go with Kleemann mid/long-tube headers or similar,
you have to get rid of primaries since there´s no room. They´re designed
that way. If you want to change secondaries to racecats, no problems but
the gains are max 5 hp. It´s been discussed here before.

Use the search-engine and you will find a lot of useful information here!

Newzchspy

I've got the Kleemann shorty headers on mine and they sound great and fitment is excellent. Don't know what they give HP wise, BUT the sound is excellent.

amgen

Nice to see you again Newz, where´s the popcorn?

tw2

Unfortunately being right hand drive I cannot use any off the shelf headers that I am aware of. The kleemann mid length require work to make it fit around the steering column. By the time I pay shipping, import tax and the exchange rate I would have more than paid for custom full length 4-1's and the merge collector they use is almost a masterpiece.

I never considered a race cat in place of the secondaries. Good idea; I would consider that if I was annoyed with the smell of gas I think.

Tump43

I have the same Kleemann set up and agree. Replaced the secondary cat's with highflow cats, kept the resonator and love the results. More power throughout, more noise outside but not in the cabin.