I apologize, if this is answered elsewhere, but I could not find it.


1. How do I need to deal with O2 sensors in case of a long tube header. It appears (from EPC), that the C63 has 4 O2 sensors - 2 main ones before the catalysts and 2 diagnostic ones after the cats. I only see 2 ports on headers. How does that work?
2. Long tube headers by principle eliminate the primary catalysts, right? Does that not create issues with CELs?
3. How well or not do high flow cats in the midsection work?


somewhat separate: Why do some folks install ceramic coated headers and think that is a good thing? Keeping exhaust gases hot longer increases speed and back pressure, so I would expect that to be a bad thing.




Thanks a lot for your help folks!

 

All very good questions, I will try to assist from my experience with headers in my C63.

Typically after header install you do obtain a CEL, your tuner will have to tune vehicle to accommodate for a few changes post header install. IE increased flow / CEL etc. Its very common and can be done relatively easily. The You are not eliminating the primary O2 sensors they are re-used when you install your headers. The secondary 02 sensors are further back in the exhaust on the Secondary cats, which are not monitored.

2nd question - No long tube headers does not necessarily mean you are deleting your primary cats. What you are doing with headers are trying to have even length runners, so your exhaust flow is smooth on all cylinders. Your down pipes are what eliminates your primary cats.

I am running Random Technology 200 Cell Catalytic converters and they are great. You do tend to lose a bit of HP, but they do flow well and assist with scrubbing exhaust fumes / resonates the frequency of the exhaust note. The C63 is a monster with headers. Its a matter of preference but I have all the exhaust note i want / need even with the 200 cell cats installed.

I also had my set ceramic coated. Im not technical enough to comment on exhaust temps and increased velocity. However, the general jist of ceramic coated headers are to protect near-by engine components from being affected by the heat created by the headers. Remember that you are no longer following the OEM header run, its a tight fit in most engine bays.

I gained a total of 95 WHP with the header + Tune combo. Same dyno's for my baseline and all proceeding mods there after. The headers netted 28 WHP on its own. ( I had the car tuned and it made 443 WHP, after the headers it was at 465 WHP and 408 LB FT TQ) On a dyno dynamics machine.

Good luck!

 

Kriston,


very much appreciated!


I have a 507 with V5 tune, so the headers will bring less than if starting from a standard (untuned) 457 hp version, I guess. Assuming I now have 530 to 540 crank hp (507 plus V5, plus ROW airboxes, plus AFE filters), that might already be around 440-450 wheel hp (530/1.2=441; 540/1.18=457). So headers would bring another 10-25 hp or so? Hmmm....


So what happens with the secondary O2 sensors? Remove them, tie the cables on to something and they don't trigger CELs?


I also thought real long tube headers go all the way down to the mid section, i.e. include what you call downpipes?


If all that is correct, then it would be very invasive, with all the consequences of losing warranty, spending 4 grand plus and so on, for not all that much gain in my case.


Something to ponder.....

 

Can somebody with header experience comment on my train of thought above? Is that about right? Thanks!

 

Wobble, the 507's with tune are realistically putting down 430 WHP. There's 1 member who put down over 440 WHP with just a tune. But the norm is 420-430ish.


As for real long tubes going straight back, no that's not the case. Most consider a true long tube for our cars are one with the collectors after the final bend down through the runner exit. Most if not all LTH's for the c63 have down pipes.

 

Basically when you install LTH you don't delete the O2 sensors. They are still there but placed differently than OEM. That is one of the reason you need O2 extensions. Technically the pre-O2 should be placed just at the end of the LTH right before the cats if you install some. The post-O2 should be placed at the end of your catless midpipes or just after the cats (if installed). Right before the resonator if you keep it or the beginning of your aftermarket catback.





I think it really depends on your set up.


You will need to get a new tune to adjust the new airflow/trim values due to the headers.
Having the header ceramic coated is as Kriston mentioned for containing the heat and reduce its affect to the already overheated engine in this confined space.
LTH is the best mod you can do N/A after a tune. Having ROW, filter and such won't gain you any or barely net HPs. Combined with LTH some have dyno'ed near 500 whp. As well LTH are just the headers... longer..lol... midpipes are separate and normally sold for extra by vendors. You can have catted midpipes or just straight or X-pipe.
The only thing with LTH for MB is the price! Very expensive as opposed to other cars. Justifications are these are piece of art and blah blah blah.... I can't really confirm since I'm not in the industry (maybe some vendors can chime in). All I know they are working. You pay to play
GL in your search.

 

Super helpful, thanks guys!

 

Abcut,


is the first picture you added from your own system? This is the first such picture I see that shows all 4 O2 sensor points, as well as cats. If so, which supplier is this from?


Finally, what catback system do most folks use? I would not want the system to be any louder than necessary. How do stock resonators/mufflers work? Or straight pipe with stock mufflers?


Again, thanks a bunch!

 

No not mine. Actually this one is a E63 set up very similar to the C63.
These LTH are American Racing Header (ARH). For the C63 they are sold under the MHP brand. The second picture are MBH headers if I'm not wrong. And you do see the pre and post O2 points. In this set up post-O2 points are not used.

Most true LTH will always have the 2 pre-O2 points. Then depending on the midpipe you choose you'll have cats or not with the 2 post-O2 points.
As for the sound LTH + OEM catback is loud. Many have tried different solutions to tone down the sound. Mufflers instead of resonator, valve controlled system, etc... I think Akrapovic slip on combined with LTH is OK if you do not want to adventure yourself into experimenting different set ups. Or IPE/agency valve system that lets you control the sound. It is really up to your personal preference.







https://mbworld.org/forums/c63-amg-w...-write-up.html




https://mbworld.org/forums/c63-amg-w...san-diego.html

 

Abcut - phenomenal post, exactly answering the questions I had (even before I knew I had them)!


MBH plus stock resonator plus Akrapovic slip on seem to be the sweet spot.
I'll talk to MBH next I guess...... Need to check into those resonated mid-pipes mentioned in the post. Did not see those on their homepage.


Again, thanks a million! I owe you one!

 

LTH's with the factory resonator and mufflers will be very loud and raspy. Some people like the rasp, i personally don't. Thats why I am installing an akrapovic titanium slip on to tone it down.

 

 

To touch on a few of your points and hopefully provide some clarity.

Running long tube headers will delete your primary cats. You have 2 O2 sensors that are prior to these catalytic converters and 2 right after them. You must have your ECU calibrated to negate a check engine light.

As for your secondary cats. You can chose to still utilize them in form of a sport cat (See pic below) if you like, or like most have connecting pipes (either straight back, or an X-Pipe) to delete them.

MBH Long Tubes with Sport Cats:




MBH Long Tubes with X-Pipe:




Doing an X-pipe back to your stock mufflers is going to smooth the sound a little but will be quite loud and raspy. All personal preference.

Another very nice option that we have been doing a good amount of is a system from iPE. Full Long Tube set up, connecting x-pipe with valve controlled mufflers. Allows you to quiet down the car if you need / want to, or open it up completely. Really nice systems.






I've done almost every combination of long tube and muffler for these cars so if it helps don't hesitate to give me a call, PM or email.

Best of luck!

 

Thanks, Tal, appreciate. I will give you a call one of these days.

 

Great thread and its answered a lot of questions i had about lth , the one thing i cant seem to get though is how you can pass emissions tests with these setups

 

My pleasure.

To be truthful there is no way you could legally pass.

 

Tal, why is that? Even with sports cats? Are they not effective enough to pass a typical emission test?

 

Wobble64, do you have to worry about emissions in your state? I too have a 507 and am contemplating headers, but I have strict emissions testing here in VA and have to worry about the O2 sensors passing/failing. Thanks for the great post!

 

MBH headers can be configured with swappable primaries so that you could go with a race cat, CA-legal cat, test pipe etc., every option is out there. So, passing the tailpipe emissions test is not a problem. The issue is the (il)legality of tampering with a closed system and whether your state requires a visual inspection.

 

Bingo

 

The Akra Setup sounds nice, but I really dislike the squared tips.


I have the Eisenmann race setup and it also tones down the exhaust note. Since Eisenmann OE manufacturers many AMG exhausts the choice was simple for me. Plus you get to retain the classic oval tips

 

Kriston, agree, I am also not too hot on the square Akra tips, but I have a BS rear bumper, so the tips would not come into play.


Overall I am just torn on messing up warranty, and spending close to 10 grand overall for 30-40 hp extra on top of the tune I already have. Need to think about this some more.

 

Update? Did you go with the MBH Headers? I just purchased a set today, including the high flow cat mid section. If you did go with MBH, how was install? Anything I need to worry about? Extensions on the rear O2 sensors?? Thanks for taking the time to write up this post!! Much appreciated....

 

I ended up buying headers from MHP (see separate thread), when they had a group buy. The price was very attractive and in terms of performance I think they are very similar to the MBH (just 4 in 1 i/o the 3-2-1 setup from MBH.
I gained 40hp at the wheels (about 50 crank) and the motor is much more hungry to rev. The sound is totally different, more like a Lamborghini. I am still considering to add an Akra slip-on to tone it down a bit.
Headers come with O2 sensor extensions for the rear pair, you do not need anything extra.

 

Fantabulous! Hopefully MBH does the same with the extensions...