Decatting.....what are the options?

[turboman]

Hi....first post from a new owner...

Well, pick up my c63 on Monday, it's an 08 plate with PP

I immediately am thinking of my first mod, which is the decat

Could you guys advise me of the most cost effective method of bringing out the rumble of the v8?

Apologies in advance as I'm sure this will have been discussed before on here but I've not found anything that gives an overview of the option

Thanks!

 

[Felstmiester]

There's no cheap way. I have the same car as you pp 58 plate and I've been wanting to decat mine for a while. I'm waiting for Phil at rebelion to finish there decat pipes so they can go on sale. If you scrimp on it you will lose power.

 

[JDMUK]

Every c63 I have heard has probably the best v8 sound on any stock car I have heard! And are very loud anyway?

If you change exhausts I would be interested in your back boxes if you sell them.

 

[turboman]

I had an e92 m3 and the common mod on these was the bypass modification on the standard exhaust....I was hoping there was an equivalent for the 63....

So what kind of costs are involved ?

 

[Felstmiester]

Think milltek do a secondary decat pipe for around £370. I know of companies that will do a decat on your c63 for under £200 but it'll also nock 10 + bhp off what your car had before so I know witch one I'd go for. The right way to do it is either slip joint or purge welded so there's no restriction inside the pipe.

There's a lot of companies out there that just but and mig weld wich means the weld then protrudes into the joint and inside the pipe thus making the inside diameter of the pipe smaller than standard. I get why you wanna do this mod tho cos I've wanted to do it for a while. Just waiting to see what phill comes up with.

 

[H20 MRV]

milltek

milltek c63 amg | eBay

Think milltek do a secondary decat pipe for around £370. I know of companies that will do a decat on your c63 for under £200 but it'll also nock 10 + bhp off what your car had before so I know witch one I'd go for. The right way to do it is either slip joint or purge welded so there's no restriction inside the pipe.

There's a lot of companies out there that just but and mig weld wich means the weld then protrudes into the joint and inside the pipe thus making the inside diameter of the pipe smaller than standard. I get why you wanna do this mod tho cos I've wanted to do it for a while. Just waiting to see what phill comes up with.

 

[H20 MRV]

What about just gutting the secondary cats? bear in mind the std exhaust is Very good, Its easy to do, Just cut hatch's with a thin rotary metal cutter then gut them and clean them up, then weld the hatches shut again : )

I have a set of down pipes (std ) arriving tomorrow and am torn between gutting and a Milltek x over...

That combined with Phil's headers and high flow cats should be AMAZING!!

 

[Felstmiester]

What about just gutting the secondary cats? bear in mind the std exhaust is Very good, Its easy to do, Just cut hatch's with a thin rotary metal cutter then gut them and clean them up, then weld the hatches shut again : )

I have a set of down pipes (std ) arriving tomorrow and am torn between gutting and a Milltek x over...

That combined with Phil's headers and high flow cats should be AMAZING!!

When you say you have a set of std downpipes do you mean a set of std cats??

 

[H20 MRV]

the very ones...

 

[Felstmiester]

So primary cats and secondary cats?? eBay?? Just been reading a thread where a guy has gutted primary and secondary cats on an m3. Knew there was no probs with doing secondary but primary I thought was a no no. According to his experience the cars better all round. But I wouldn't wanna take that risk with the c63. But if I had a spare set like yourself that would be great. On second thoughts I'm sure I've seen them on ebay.

 

[H20 MRV]

I will just gut the secondary cats and see what its like, I did this on a M3 and it was a great improvement !

 

[Felstmiester]

I will just gut the secondary cats and see what its like, I did this on a M3 and it was a great improvement !

So was it cost effective buying the standard set up over the milltek sec decat?

 

[H20 MRV]

£270 delivered and it will cost £25 to get the hatches welded up and my mates garage will fit it for a few beers,

But more to the point I still have the std system and I can always sell the modded system.

 

[Felstmiester]

Right. As I haven't got underneath mine or took much notice of the set up, looking at the pic of your bargain purchase and looking at the milltek secondary decat ( witch I very nearly brought ) I thought the milltek was a direct fit job by without having to cut the standard set up but now it's clearly not the case. So what you have in mind is by far the best option. Your one step ahead. Now I'm on the lookout for the same lol.

 

[H20 MRV]

this gives you the idea, exempt this is the primary's of course.

 

[H20 MRV]

And of course if the hatches are cut on the top Mr Merc will never know...

 

[turboman]

Really like the idea of gutting the primary cat.....surely that would be a very cheap, simple job if I used the existing exhaust?

Does anyone have any sound clips or links to vids to illustrate the sound this mod produces?

Ta!

 

[BTB 500]

When it gets to 3 years old it surely won't get through the MOT emissions with gutted cats?

 

[moonloops]

When it gets to 3 years old it surely won't get through the MOT emissions with gutted cats?

A perfectly tuned engine will pass every test known to man, with or without cats

 

[Paparazi]

So what does the catalytic convertor do?

1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2
2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O.

Catalytic reaction at high temperature as the noxious gasses/chemical by-products pass through ceramic monolith coated in precious metals.
As you can see above...the 'catalytic reaction' CHANGES the chemical composition of the pollutants as they pass through the CAT......no amount of engine tuning can replicate that function.
Martin