CLK55: Secondary cat delete, MOTs and Track Days

Page may contain affiliate links. Please see terms for details.

breeze247

Active Member
Joined
Apr 15, 2016
Messages
62
Car
CLK
I have a 2003 CLK55 that I would like to get a bit more noise from.

I can see that the standard first step that most people take is to delete the secondary cats.

Two potential issues:

- MOTs: I understand emissions will be fine but at some point in the future, testers may become more strict on the visual test. I think the answer here is to gut the cats with a weld on the hidden side.

- Track Days: I have a concern that the extra volume will be an issue with noise meters. I do one or two each year but it would be a real shame if the car were too loud. This is the biggest issue for me.

I like the thought of something that is reversible, so keen to hear if there are any options that are.

Thoughts? Experience with 55 non Kompressor motors or 63 motors in particular. Not looking for power and would prefer not to need to worry about re-coding for EMLs etc.

Thanks in advance
 
Where do you track it? - Can you just lift when you go past the microphones; they're usually easy to spot.
What about trackday bungs to quieten the exhaust? - I've never had to run them in the Nissan, but I'm certainly aware of the option.

I suspect that a friendly MOT tester would claim that they didn't know the car should have secondary catalytic converters, so didn't fail it as the primaries are still in place.
What about replacing them with a "sports" cat (i.e. larger pore size to give greater airflow through the same PGM loading)
 
Go the whole hog and remove the resonator as well:banana:. It won't be unduly loud (My E55 isn't) Re the cats, gutting is preferrable if you worry about future MOTs or you could always store them in your garage and refit them if needed. No problem with an EML unless you mess with the primary cats.
 
Track days at Castle Coombe test the car static in the garage. my mate had trouble getting through but he came prepared with an ugly silencer pipe that he just bolts on if it fails.
 
Where do you track it? - Can you just lift when you go past the microphones; they're usually easy to spot.
What about trackday bungs to quieten the exhaust? - I've never had to run them in the Nissan, but I'm certainly aware of the option.

I suspect that a friendly MOT tester would claim that they didn't know the car should have secondary catalytic converters, so didn't fail it as the primaries are still in place.
What about replacing them with a "sports" cat (i.e. larger pore size to give greater airflow through the same PGM loading)

I’ve driven at most of the Southeren UK tracks over the years, although like I said, these days far less. Donington Park would be most likely and that is drive by and static.

To be honest, lifting off would ruin it for me. I think bungs aren’t really worth the hassle for my type of usage. Cost is also a factor.

A lot of people say that MOT enforcement may change, so I am cautious there too. I would be happy to buy a set of replacement cats and gut those, although they are rare.

I think part of the issue is that lots of AMG cars aren’t tracked, meaning that experience with this type of case is going to be limited.
 
Go the whole hog and remove the resonator as well:banana:. It won't be unduly loud (My E55 isn't) Re the cats, gutting is preferrable if you worry about future MOTs or you could always store them in your garage and refit them if needed. No problem with an EML unless you mess with the primary cats.

Thanks for that - yes I was aware that EML would be fine if retaining the fronts.

Unless you can tell me you have done all of the above and then tracked the car I will refrain from taking your advice just yet!
 
Track days at Castle Coombe test the car static in the garage. my mate had trouble getting through but he came prepared with an ugly silencer pipe that he just bolts on if it fails.

Yes, that is an option, but again we are talking about very limited ha
Track days at Castle Coombe test the car static in the garage. my mate had trouble getting through but he came prepared with an ugly silencer pipe that he just bolts on if it fails.

Yep - as above, it doesn’t make massive sense to start buying bolt in silencers. My understanding is that they can affect power too.
 
For context, a friend of mine has an E92 V8 M3.

He went down the tried and tested route of modifying the standard exhaust (I think the back box) and that gave him additional volume without causing a problem on track days.

I was hoping for similar.
 
Oulton Park is on the pit straight (I think as you go past the commentary box), so you don't get back on the power at Lodge and hammer it as hard as you like at the bottom of the hill.
 
Should be fine. I ran 2x C55's with secondary cat and res delete. I took 1 on track twice at Oulton park, but it only has the resonator delete at the time. It was miles away from the limit. They only test it at 3-4k revs whilst parked up, I cant see it being a problem on a track either, after seeing and hearing a new Audi R8 v10 that was fine and it was much louder.
 
Its funny how people on here are saying that fitting an auxiliary exhaust to drop down the db on a track day will 'affect power' but are willing to take their foot off the gas once or sometimes twice each lap to 'fool' the sound test.
 
Its funny how people on here are saying that fitting an auxiliary exhaust to drop down the db on a track day will 'affect power' but are willing to take their foot off the gas once or sometimes twice each lap to 'fool' the sound test.

I’m willing to do neither!
 
While on the subject of 'noise' on track days, its only an issue because intolerant people saw fit to buy a house near a race track then moan about the noise ! Most (almost all) of race tracks in the UK are positively ancient, i:e been there before 'the houses' and many are derived from old airfields. As a result most are restricted in their allotment of 'noisy days' per year . Noisy to whom exactly ? oh that's right the NIMBY who bought a house near a race track.

Reminds me of when Madonna (remember her) Bought her UK country pile near Compton Abbas in Dorset. She had two major complaints , one was that 'people' were walking along a fence outside her property and the noise from the nearby airfield.

The Public right of way the 'people' had been using had been there for donkeys years The airfield since 1962.

Maybe she should have had her lawyers look a bit closer at the property before paying £9Million for it ! incidentally it was reported that she wanted to buy the airfield and offered £800000.00 for it. Its still there and she has gone.

She gave the house to Guy Richie as part of their divorce settlement. Nuff said.
 
Agreed. - If you've been living there since the last world war, then you can legitimately complain about the noise of a track. If you've bought (or built) in the last 70 years, then the track/airfield was there first and was probably the reason the property was cheaper than you'd expect.

Personally I'd just do without the extra volume. - Loud exhausts get tiring very quickly; I had to take the Nissan back and ask for another box to be put in, and I still wear earplugs if I've got a long drive to do.
 
Unless you get rid of the entire backbox (i did it was epic) you wont have any issues with track day db's.

Due to stricter mot regs id say gut the secondary cats and remove the resonators. It will sound nicer but still a lot quieter than a modern amg.
 
Unless you get rid of the entire backbox (i did it was epic) you wont have any issues with track day db's.

Due to stricter mot regs id say gut the secondary cats and remove the resonators. It will sound nicer but still a lot quieter than a modern amg.

When you say resonators, are you talking about the contents of the cats or the other exhaust boxes?
 
I occasionally track and Vmax my W211 E55, admittedly SC'ed car,
I have OEM primary and secondary cats and res
ounatuer removed, Kleemann headers, there from bespoke EMP exhaust , with 200cell race cats and OEM rear boxes, MOT done at Mercedes last few years, no problems to date, did swap the rear boxes to C63 boxes for 24 hrs last year, night mare, black flagged for noise @ Goodwood immediatly, and the general driving drone was awful, took it back to EMP and had the OEM rear boxes put back the following day, quite content to how my car sounds now, very quite in road driving but big sound on track, it,s been virtually trouble free to now. TBH, think there are multiple ways of going about your quest, just choosing the right way for you, best of luck with it all.
 

Users who are viewing this thread

Back
Top Bottom