Removal of all Cats on Merc V8 - MOT worries?

[rgv250ads]

As title really, ive already got 2nd cats and resonator box out and replaced with straight pipework and an x-pipe.

I'm considering the kleemann headers and a suitable eurocharged tune via MSL performance in Birmingham.
This involves the complete removal of the primary cats and post-cat Lamba Sensors - I am certain the car will fail yearly emissions.

Has anyone in the UK had all cats out on a Merc V8, headers and an ecu tune and does the car pass or fail. Is it hard to find an MOT centre who will turn a blind eye? Anyone know of an MOT place in Herts/Beds who MOT Kit/Modded cars and will pass such vehicles..... if you dont want to name them message me.

Car is 2005 SLK55.


Feedback sort. Cheers all.

[daveenty]

MSL also do MOT testing so I'm sure that Acid would be able to advise on this.

[rgv250ads]

Yes it will likely fail, but MSL is 200 Mile round trip - not really keen on doing that every MOT. So is it common for folks with these mods to go to normal MOT stations or are some known in the home counties area who are friendly over such issues........

[ghibbett]

Pffft, 200 mile round trip is nothing for an MOT. Make a (very short) road trip out of the journey.

[slk 32]

I own a 2006 slk55. I had an X pipe fitted and secondary cats removed last year. This August I had kleemann headers fitted which necessitated removing primary cats.

This made it insanely loud.. but not in a good way. It sounded like I had no exhaust at all and was essentially undriveable with a really harsh drone at 3k rpm.

In retrospect it would have probably been okay if I had not initially removed secondary cats and fitted the X pipe. I took it straight to infinity exhausts and had them remove the X pipe and and a small silencer box with internal X pipe and a pair of 100 cell sports cats.

It now sounds great and is a lot more driveable

however...

i took it to my local garage and asked them to run the mot emissions test.it passed all apart from the co2 one.. by some significant margin as it was over fuelling due to the kleemann remap

yours will fail with no cats and be undriveable with the noise.

I would suggest getting the mot done prior .. This at least gives you some time to sort it

good luck and let me know how you get on!

Edited by slk 32 on Saturday 4th October 06:37

[rgv250ads]

Perfect information to find out now - exactly what web forums are priceless for !

I am happy with the noise today at all RPM with the 2nd cat delete and resonator out, X-pipe and Eurocharged ECU tune - and i have no intolerable drone at crusing speeds either. There is a tiny 'hummmmmmm' but completely acceptable. Completely.

i wouldn't be adding headers and a further ECU map for additional noise. I'd only want it for performance.

• However**, not prepared to spend further money on the exhaust to get it to MOT compliance after the header install. - and on top of that, having to then tackle the issue of quietening it down. Just adds more and more £££ to acquire 25BHP. i've already had it dyno'd at 390HP and this is decent figures for the little rocket.

I really appreciate you posting this honest opinion SLK32, as this is the sort of concerns and information that are really needed to make the decision. It is so tempting to 'sod it' and just get these mods, but then be full of regret and what not afterwards.

Cheers.

[rgv250ads]

slk 32 said:

i took it to my local garage and asked them to run the mot emissions test.it passed all apart from the co2 one.. by some significant margin as it was over fuelling due to the kleemann remap

What do you intend to do to get it emmission friendly, larger cats? different tune?

Overall would you say it has been more hassle than it was worth.
Who installed the headers out of interest.

[slk 32]

If I'm brutally honest, there were a few dark moments when I did think "what the f**k have I done?!".

This was driving back from having spent £5k on remap, cams and headers and sitting in traffic with wisps of smoke coming from the bonnet as occasional gobbets of oil would leak from the rocker cover gasket and vapourise on the exhaust headers.

The biggest Ballache by far is the emissions now.. having spent £300 on a perfectly good X pipe having to rip it out and add new sports cats and silencer (another £400!) and its still not MOT compliant is not good. As this is due end oct i really need to come up with a solution.

Is it all worth it? Again if I'm honest I'd say stick with the remap and X pipe.. After that Iit really is the law of diminishing returns.. i was rather spoilt with the slk 32 as the supercharger mods were quite straightforward .
as my end game us to fit the kleemann supercharger it made sense doing the other stuff first and now I've started I've got to see it through.

That's the beauty of man maths though.. i see from your user name you are a two stroke fan..as a TZR 250 reverse cylinder owner if I just wanted a bike I could ride a nice four stroke twin..but that just wouldn't be the same. Sometimes you just have to follow your own road!

[rgv250ads]

Yes I raced two rgv's from 2005 to 2008.
They were supertrick, dry clutches, close ratio boxes, kit pipes, custom ignitions, ran on avgas and were wonderful when working spot on. Getting them in the sweet spot was a huge challenge and rewarding. After a few seasons I swaped to MRO minitwins and did 3 seasons, won the MRO title twice.

Have a massive soft spot for two strokes.

Thanks for the honest postings. As I will never do the supercharger, I have sacked off the headers now. I just dont want the hassle of trying to quieting it down and catting the remaining system to get it mot friendly. Sure, could find a friendly mot place to get the paperwork annually but its getting the boom or drone under control that puts the nail in the coffin. We use the car for fun and fair weather cruises so having a drag car does not appeal.
What are your plans to get it under the co2 barrier?
Love the tzr reverse. Wish id have gor a tz250 and kept it. Becoming really desirable now.