Howdy gents,

Due to Covid 19, I have had a lot of time of time to think, and browse the internet listening to other peoples C63's.
I have decided to fit long tube headers to my car in the near future because from what I have heard, they make the C63 sound even more amazing, and have the added benefit of giving you an extra 30-40hp(correct me if I am wrong).
From what I have read, it's a fairly involved and time consuming process getting the old headers off, and new headers on. Is there anything worth addressing whilst the mechanic is in there? i.e changing belts, pulleys, injectors, gaskets etc etc. My car is a 2011 sedan, which so far has given me ~30,000kms of trouble free motoring(currently at 108,000kms ~ 67,000 miles). I was more so looking to do some preventative maintenance/mods and save me some cash and time while the mechanic has the engine open. I am aware that this is a bit of an open ended question and is dependant on budget. I don't want to replace my cams or lifters because that will cost me an absolute bomb, and from my experience so far, they seem fine. In saying that, if there is a good reason/benefit for changing the tappets to the SLS or SLS black series tappets then I would explore that option.

In addition to headers, I am toying with the idea of running 82 or 85mm throttle bodies after reading a few posts on here about throttle bodies and velocity stacks. Someone mentioned that in order to get the most out of TB's, I would need velocity stacks. How accurate is this?
Would I need to upgrade my injectors and fuel pump if I change to an 82 or 85mm throttle body? Those who have changed there TB's, what are your impressions so far? worth doing? would you recommend doing them, and would you do it again if you had the option?

Finally, I am thinking of removing my secondary cats for even more sound, and possibly performance. Does removing the secondary cats offer any more performance?
For reference, my car is basically stock, with the exception of having a resonator delete, K&N air filters and a tune, netting me ~ 385WKW, or 480WHP. My dyno run was done on a mainline dyno if that makes a difference. Any modifications I do will be followed by a re-tune and a couple of dyno runs.

The setup I am thinking of would be long tubes, secondary cat delete, and then out into the mufflers. My resonator delete consists of straight bits of stainless going straight into the mufflers. With a secondary cat delete, can I do the same thing? i.e cut out the cats and chuck in some straight pipe goodness? Or will I need to use a H or X pipe? I don't want to take away from the AMG sound, just make it louder/more prominent. I would hate for it to end up sounding like a holden commodore.

 

While your in there do your engine mounts. I recommend ECE mounts. Running them on mine and I am completely in love with them

 

Are you not worried about emissions and check engine light with no cats?

 

Also, with no cats and no resonators that will be LOUD
You don't drive daily do you?
I bought my car without resonators and didn't like the drone so I found a factory exhaust, put resonators in but removed secondary cats

 

Also, without cats, you will smell like fuel...so will everything around you.

I was in love with the sound, but smelling like fuel was a major turnoff.....ordered the high flow cats within DAYS of not having them.

 

I was under impression that removing the secondary cats wouldn't trigger any CEL lights, only removing the primaries would. Eh, emissions dont worry me, our cars don't get tested. If the cops stop me, yellow sticker my car and then it has to be inspected I'll work something out.

 

Car is currently my daily, haven't noticed any drone with my resonator delete.

 

Do long tube headers remove the primary cats?
would you reccomend high flow 100 or 200 cell cats for the primaries and or secondaries?

As much as i like the smell of 98, smelling like a petrol station isn't something i want to do on the regular

 

Do long tube headers remove the primary cats?
would you reccomend high flow 100 or 200 cell cats for the primaries and or secondaries?

As much as i like the smell of 98, smelling like a petrol station isn't something i want to do on the regular

 

Long tube headers remove the primary cats.
My car has IPE headers and mid pipes. So both the primary and secondary cats have been removed. This goes into the factory resonator boxes, and then the rear boxes.
i don't have drone.
I can't say I have ever really noticed a petrol smell. I daily drive my car.

 

+1 no cats is the way to go. I have MBH headers and castles mid pipes with an x pipe. So zero cats into the factory resonator and factory rear piping and mufflers. Sounds amazing. Iv Had so many compliments on the sound it’s crazy. Highway speed 80 no drone. If you get on it all he’ll breaks loose. I will say there is some exhaust smell with no cats at stop lights with windows down and the wind blowing right. I don’t care at all I love it and I run 100 percent e85 and it’s smells great.

 

I don't have my resonators, had then removed and then my old man man sold them for $20 without my knowledge....so that was fun to find out...