skaarlaj

I see a lot of people end up going with headers and "tune" on their C63, but "most" or damn near "all" seam to end up going completely cat-less. I've noticed a lot of those people usually end up doing other mods to try to tame the noise afterwards too, just curious if running catted mid-pipes with long-tube headers into the factory resonator would be less obnoxious than without cats? I added cats to my mid-pipe on my 04 Cobra with a nice sounding out-come and no seat of the pants power loss whatsoever, and I'll just venture to say this car breathed more than probably 95% of the cars on this board, just to clarify that I don't think the cats are much of a restriction.

G55AMG

I just got the headers, an I'm going to used high flow cats with them.

Merc63

An X pipe is necessary for performance and noise.

High flow cats would help too. They will cost you power though.

A loud exhaust is a powerful one

PaulWdz

Good quality 200CEL stainless steel metallic cats will not take away any noticeable power. You might see it on paper, but you won't feel it much. And, they will take away alot of the noise. If you run them with the factory resonators it will still be loud but not like catless. Catless is so obnoxiously loud and IMO sounds like crap.

This is a good cat:

http://www.stainlessworks.net/produc...x-hi-flow.html

skaarlaj

I'd buy that if I didn't see so many fart can cars, and 1978 chevy trucks with cherry bombs running around, I really believe some of the loudest vehicles I've seen have had less than 200 hp, seriously!

bhamg

This. On the dyno the difference between CA-legal primary cats and test pipes is ~ 20hp.

Merc63

A free flowing exhaust is loud. A loud exhaust is a powerful one..

Why do you think an F1 car will break you ear drum?

I'm not talking about some guy with a Chevy truck with blue bombs on it. In talking performance.

Aresh

you may still get the CEL with high flow cats. Anyone experience otherwise ?

PaulWdz

Exactly - throw in some good 200CEL cats and it's more like 10-15hp. Not something you are ever going to really notice.

CoolBDPhenom03

TBH, I'm more of a dog person.

Seriously though, when I swapped out my midpipes for hi-flow cats, I didn't get a CEL while I was smogging it.

skaarlaj

There's quieter cars that will eat probably any one of these C63's for lunch, and there's certainly some bad-*** cars that are loud, but IMO, if you're under 800hp, it certainly doesn't "have" to be loud.

skaarlaj

What do you mean by "smogging-it", just curious.

Merc63

You're not understanding what I am saying and comparing apples to oranges.

The less restrictive (louder) your exhaust the more power.

skaarlaj

Try running no exhaust manifolds or headers, tell me how that runs, and I'll even let you "tune" for it hahahahaha.

I hear what you're saying, but many, many vehicles are way louder than they need to be, and I don't want to be "that guy" with the 400-500rwhp car that's as loud as a friggin dragster.

skaarlaj

Take a look at that goofy akrapovic video on youtube with that valved exhaust or whatever it is, I'm betting it's one of the louder ones around, but nowhere near the fastest, or most powerful. What do you think makes more power a Wisetech supercharged C63 with factory exhaust, or one with headers and straight pipes without a blower, and yes if you open up the exhaust it will make more power, but it "does not have to be super loud" to breathe super good.

G55AMG

4ramin is a member here and he is using MHP LTH with X pipes and high flow Cats.
He can tell you more.
JV

CoolBDPhenom03

Since I was bringing an out of state car into CA, I was required to pass a smog check before I could register it.

skaarlaj

Gotcha, thanks.

NellyRod

Will 200 cell cats keep the exhaust fumes from trying to kill me at a red light?

skaarlaj

I added cats to my 04 Cobra's exhaust and it helped with the smell and sound, and didn't effect my power negatively at all, "that I could feel".

skaarlaj

If I do get headers, they will have cats down-stream of them. I will def. report back when / if that happens.

Ezec63

Why pay all that money for a 50hp modification to pay even more money to remove 40% of that mods power(20 hp). Doesnt make sense to me and its not about the "look at me" exhaust note that Merc63 is talking about. This is an N/A car headers are big power adders and if you want to optimize OUR setup you should run fully catless headers with a 3 inch x pipe it has nothing to do with other cars being faster and quieter.

skaarlaj

I just can't imagine a measly 500 hp engine being restricted by high flow cats. If this was engine was making "huge steam" I'd buy your 20hp figure, but only with a dyno sheet from the same day on the same car on the same dyno, without much change in the weather. Sorry

skaarlaj

Dyno sheets, or track times please, for the next person claiming power loss from high flow cats after headers. And not an advertisement.

bhamg

My semi-informed guess with 200 cell HFC's on this csr is 5-7 hp max loss.