nrgy

sflgator, the stock piping is 2.25". The reason I'm running 3" high flows is because the mid pipes from MHP are 3" up to where they mate with the stock resonator.

You might want to look at Random Technology for high flow cats. They are fairly well known for producing high quality metal cats although they are fairly pricey, but they make them in pretty much any application you could want. They have universal sizes that should work too.

Btw, it is possible not to have to weld the cats in. You could use clamps with the right connectors. This is how my setup was designed, but my installers did recommend I tig weld them in to prevent any possible leaking and to eliminate having all these clamps, which is what I ended up doing.

AMS Performance

If its 2.25" then use the 2.5" cats. Outer diameter of stock piping is actually closer to 2.35-2.4" so 2.5" is close enough.

I agree, its always much better to weld than use clamps/flanges. Typically those joining methods leak much more.

sflgator

Thank you for all your assistance, nrgy and AMS...I think I may get some high-flow cats then!

BTW -- check this out...the high-flow cat on eBay that AMS pointed us to...




AND, the Random Technology universal high-flow cat on their Web site...

They look identical; I wonder if the eBay one IS the RT high-flow cat!!!!

nrgy

Hmm, good question. You know, if the price is significantly cheaper the eBay ones might be worth a try. The ones I have, however, are 3" diameter all the way across, I think mainly because of fitment issues, since the long tube headers move the primary cats to a different location. If I could have fit the ones you posted I would have given those a try.

soldier2304

Let me know your plans dude! Seems like you've finally dig up enough info to work something on your exhaust... Let me know how it goes.

sflgator

Will do; may be going this high-flow cat route now.

AMS Performance

Both RT and TB are good cats, it really boils down to price and the TBs are significantly less expensive and still made from high quality stainless steel (and metal cores of course).

either way you can get a pair of cats as cheap as $150-180 depending on the dealer so really there is no excuse not to get them. Report back how you like them.

Hope that helps

sflgator

The lowest price online I see for the 2.5" RT high-flow metal cats are $206/each, so I think I'm going to order the ones for $90/each; I guess those are TB -- which stands for?

I sent a message to the eBay seller (magnumexhaust) but haven't heard back yet. I also found similarly priced high-flow metal cats (that seem like they are of similar quality) on eBay as well...

http://cgi.ebay.com/ebaymotors/Stain...4506.m20.l1116

http://cgi.ebay.com/ebaymotors/High-...4506.m20.l1116 (made by ECT Catalyst)

Any thoughts on these?

Also, doesn't your company, AMS make high-flow cats? Are they just for the Mitsu EVO? Would they not fit the C63 AMG?

AMS Performance

I wouldn't trust either of those links, one doesn't even provide a picture of the core and the other looks like metal core but it looks like a 400cell. Go with magnum exhaust TB ones, they have great customer service and dozens of MBworld users have used them with no problems. $180 shipped for the pair is a tough price to beat. TB = Thunderbolt, most of the universal cats on ebay are made by them. They are 49 state OBD2 compliant.

No, we do not make high flow cats, we merely recommend them to our customers for improved performance. They perform very well with our performance headers & etc. AMS has no relation to the Mistu Evo AMS tuning company.

Thanks.

sflgator

Gotcha. Thank you!!!!

FYI -- it looks like Thunderbolt (Canamex Exhaust) is based in S. FL; is the same TB you're talking about? If so, I've seen many other TB 2.5" high-flow metal substrate cats online for much less...$55/cat (e.g. - http://www.performance-curve.com/ind...OD&ProdID=1180) ...are these the same as the one from magnumexhaust?

http://www.thunderboltperformance.com/index.html

http://www.thunderboltperformance.com/newprod.html

mprsev

I have been following this thread and the posts by AMS as they have been very informative. I am curious though about the C63 mufflers versus the E63 mufflers as I have read that the AMG mufflers and resonator are for the most part pass through so most of the restriction and my guess exhaust note is based on the headers and cats. So is there a difference in headers and cats between the E63 and C63 as the sound note between the two is significatnly in favor of the C63.

sflgator I cannot wait to hear how the high-flow cats work out. Are you just going with the secondary or all four?

sflgator

Just the rear cats for me; I figure it should still increase the flow and add HP/TQ...10-15 WHP/RWTQ seems to be the consensus among most professionals. I know most ppl who replace the DPs with high-flow headers also replace (or eliminate???) the cats with high-flow cats, but I am not touching the primary cats.

AMS Performance

Correct, that is the same one. Careful though, sometimes some sellers market them as high flows without showing you the actual picture of the cores. If its metal core it will be a grey metal spiral wound core, if its ceramic it will be a beige/pinkish grid like pattern.

If you can find them for less then by all means do so, as long as its the TB brand cats you should be fine. Just confirm by having them take a picture of the core itself for verification. If you can get for $110 shipped that's a steal, for the longest time only Magnum-exhaust was selling them but I guess a few others have come on board in the last month or so.

Always glad to help,
~AMS~

P.S. I've been requesting them to do the angled primary cats in high flow 300-cell form for some time now but to no avail. Maybe if enough of the Mercedes community emails them and keeps requesting it they will do high flow 300-cell primaries as well in the angled primary form (8" long body saves a lot more space than the 11" standard cat and makes it much easier on many of the AMG models to do high flow primaries, although its not necessary for some AMG models which can use the standard straight 300-cell cat form).

sflgator

Just ordered the TB 2.5" high-flow metallic substrate cats...$120 shipped! Will let everyone know how they are after I get them installed. Thanks again AMS!!!!!!

AMS Performance

Sure thing, Be sure to report back to the community about your findings . Remember, it may take up to 2 weeks for the cats to fully settle in so reserve judgment for a few weeks. A before/after dyno would of course be best . I wouldn't be surprised if you broke the 15HP barrier on this mod alone since its the 6.3L.

~AMS~

Brian GT PRO

If you want to adhere to the letter of the law, replacing the cats (ANY) on the C63 is illegal per the ARB.

What it boils down to is personal preference. Will the car's emissions be cleaner by adding the highflow cats instead of going to straight pipes? yes, Is it legal to do so? No. So either way you slice it, removal of ANY sort is illegal. Period, unless used for testing, or off road use only.

Both CARB and the EPA do not allow the replacement of a catalytic converter with non-exempt "high flow" performance replacement unit. In fact, it is technically not legal to even replace a converter unless it has been proven by technician to have failed, and then it can only be replaced with an exempt OEM equivalent unit. It is illegal to remove a properly functioning catalytic converter and aftermarket catalytic converters are not legal for installation in California on OBD II vehicles (some 1994 & 1995, and all 1996 and later vehicles).Currently, 16 other states have either adopted, or are in the process of adopting, California's strict emissions standards. These states include New York, New Jersey, Massachusetts, Maine, Connecticut, Rhode Island, Pennsylvania, Vermont, New Mexico, Oregon, Washington, Maryland, Florida.

tanktube67

Check royalmuffler.com

AMS Performance

Hello Everyone,

Since I have been getting so many PMs I decided to do a little graphic to help everyone better understand what to do. Hope this helps....

digo63

great thread guys, got me excited to mod my c63 09 it has 1400 miles now and i'm thinking if i should mod it exhaust now or wait till i reach 4000 miles or more?

if so anyone know experienced installer/mod shop for c63 amg in San Francisco/san jose ?

i would like to changed my 2nd cat to high flow cats from RT and hope to be done in good hands.

Thanks Team

sflgator

Great diagram...that's AWESOME! Thanks for posting that.

sflgator

Updates...just installed my Thunderbolt high-flow cats today and a few brief observations...

1. Slightly "throatier" exhaust sound.

2. The oem stock cats are in fact higher quality, metal substrate inside, although they are not high-flow...I was a bit surprised although I shouldn't have been given the incredible quality and sound from the the oem stock exhaust system.

3. Install was a bit more complicated than I thought; they had to cut a little off the high-flow cats' intake/outtake pipes and add new, short mandrel-bent pipes that connect the cats to the pipes just behind the resonator (since the oem stock pipes don't connect straight out).

4. Since I've heard that it could take up to 2 weeks to get a better sense of any possible gains, I will post an update later. Unfortunately, I do not plan a post high-flow cats dyno.

mikep17

where in florida did u get them installed? I am interested in doing this. Im in west palm beach

dlbello

Does anyone know the difference between the K2 High-flow CATS compared to the "magnum exhaust TB".... I understand the K2 package has quality CATS, which should pass an emission testing in NY... does anyone know different? TIA

sflgator

I believe the Kleemann K2 high-flow cats are actually the primary cats that go with their short DPs vs. the other high-flow cats (like mine) which are the secondary cats just before the resonator further downstream.

hotcorner216

California legal high flow cats for 2008 C350?