emericr

AMMO: I agree with what you are saying on the overpricing but the LT headers are not just a bit more, they are double the money i.e $4K which I also simply refuse to pay.
Super did test the GT-pro downpipe and showed no gain (I understand he did not have the X pipe). However his pricing is a lot more reasonable.
This is driving me crazy. I would like to believe taking it out cats would yield a hp gain. I did it on my S4 and it increased rwhp by 20.

Sincity

I believe Jeffield replaced his DP, primary & secondary cats with a 3" pipe (no x-pipe) from the exhaust manifold to the resonators. Basically this same section. However, he did not have a before dyno and did the exhaust and tune on the same day.

emericr

Yes, you are right that Jeffield did this and his car sounds awesome. All I am looking for is an increase in sound above 3.5K and little intrusion and without drone at cruising. I am also looking for some increase in horsepower, obviously not as much as headers but we are not talking about the same price either.

Sincity

It has a loud bark for sure and it's prescence is known while cruising down the freeway when I was in his car. I am looking for something not as loud.

emericr

Are you saying that his downpipes at cruising speed on highway (lets say under2.5K) were causing a substantial increase in noise inside the cabin?
I do not remember if his set up kept the resonators and back mufflers?

Sincity

Substantial is very subjective and the best I can describe it is that I can hear the exhaust at cruising speed. Not sure what I can compare or relate to for better reference. But revving while standing outside is loud with a hint of raspiness like Super described it when he was working on his DP project.

I would really like to see how this Motorunion setup will perform and sound with a set of 3" high-flow cats installed. The regular price of this setup is a bit steep. There used to be a speed shop here in Vegas that was around for forty something years before the recession killed it even though the family owned the property that the business was on. I had them build me something on my '07 GTI using mandrel pieces and his welds were every bit as good as these. They had some beautifully made custom headers on display. Too bad they are no longer around because this is an easy project that he could have built. But in all fairness, that speed shop would have had difficulty reproducing those round flanges that AMG decided to use.

emericr

Thanks for the feedback. We will have to wait for testing on hp claims but I am wondering if the easiest is to just delete cats and resonators for about $300. I am getting fed up of waiting lol

GHAZAN

Your passing misinformation...
- LTs are in the 3ks, Kleemans 2500
- Super had a custom 2.5" downpipe - never dynoed but got 1-2mph at 1 track day, so theoretically similar gains to the piece above ~25rwhp
- GT 2ndary delete Xpipe shows little peak ~10hp, but a little more under the curve

Probably easiest/cheapest to delete 2nd cat with a straight pipe for 100 bucks if your not interested in removing primaries

emericr

Ghazan: thanks for making sure I am passing the right info. Sorry for not being 100% clear but the headers I was referring at $4K are the MHP ones which have proven to provide the biggest hp and trap speed gains.
Taking Super's testing, he achieved 12.06 and 117mph with custom catless downpipes.
He achieved 12.03 and 116 mph with X pipe and manifolds
He achieved 11.6 and 120 mph with MHP headers.
I admire Super's for his relentless pursuit of hp and faster times but I am just putting the gains in perspective to the dollars spent.
I do not know the gains Kleeman claims. Please share posts if you do but I would love to get the gains MHP gets for $2,500.
So as far as I know now, here's my summary in order of $$ spent:
-X pipe to replace secondaries: increased noise and let's say around 5hp. No gain in ET and trap speed. Cost: a few hundred bucks or more if GT-pro for the benefit of easy swap.
-Catless Downpipes: Very loud. Around 10-20hp. a few tenths and mph improvements. Cost: range from $1,400 to $1,600 including install.
-MHP headers: Very loud. Around 50-60hp. about .5 second and 5mph increase. Cost: $4,500 including install.
It all depends what you are looking for but IMHO, the MHP headers do not make financial sense as they represent 10% of the price of the car or 10% of total lease payments on a new GTR.

SonnyakaPig

To me, the power gains seems very curious. Here's why, the stock runs on the dyno used for this test showed torque way above hp. That's not how C63's function.

I understand that all dynos are different and that's why the low reading Dyno Dynamics doesn't concern me at all. Dynos are just a tool and a Dyno Dynamics dyno can offer just as much in the way of measuring gain as a DJ or Mustang.

But here, the power curves seem all wrong. It would be one thing if the dyno run after the FMU x-pipe install showed higher tq than hp, but that's not the case. Here, the tq curve is higher than the hp curve in the stock run as well as in the FMU x-pipe run.

Further, how can a header-back exhaust mod provide over 20 rwhp when the tune remained the same and the C63 is detuned to begin with? 10 whp, maybe, but over 20 rwhp, that's a tough sell in my book.

I don't think the GB pricing is too far off from a good price point. Maybe 2-3 hundred bucks less would be good.

Edit: Another thing that is very difficult for me to accept is the rwtq increase: 25 ft lbs? C63's do not appear to make extra torque as easy as extra hp. For instance, aftermarket tunes can net you over 410 rwhp on 91 octane gas. But rwtq will often be no more than 386 rwhp on 91 octane. Sure, some C63's with tune and other mods and 93 octane gas have 400 ft lbs rwtq, but everyone knows torque is not given away with this NA motor. So, how can adding this midsection and x-pipe give a 25 rwtq increase? If this is valid, people should stop worrying about price because this is almost as good of a value as an aftermarket tune in terms of increasing rwtq. But, I would need to see more dynos or mph at the track to be convinced.

RStevens63

emericr,

Think of it like this. AMG gave you 451HP for ~72K out the door maybe higher or lower but avg.

That's $160 per HP stock as delivered.

With MHP Headers (501HP/76.5k): $152 per HP

With MHP headers and tune (580HP/79.5k): $137 per HP

The more you mod the lower the $ per HP ratio goes. It seems AMG gets the majority of the $ for delivering the least amount of HP.

Again 451 HP stock for $72k is $160 per HP.

$6995 for ~130HP is $54 per HP gained.

Another way to think of it. We all know modding our cars is a losing proposition, but we do it anyway because we enjoy the performance

RStevens63

Makes a lot of sense. That's a huge increase from a mid pipe.

About pricing, you can't compare mods to a C63 to those of a Mustang GT for one reason alone volume. Mustang GTs are 20:1 or more vs C63s on the road. Can't have it both ways, low volume low price doesn't happen.

SonnyakaPig

You know, I'll be the first one to say how excited I am to have another hp option for this car. And I want to be wrong here. Because if the sound is nice, this looks like a great option. Price isn't too rediculous for the purported gains.

SonnyakaPig

This is 100% true.

And the welds do look beautiful on this piece.

NOSONYXC63

As soon as I get my set I will post my results... I have a DynoJet I always go to...

SonnyakaPig

Very cool! Can't wait to see.

What's your baseline at that DJ?

Sincity

Are you tuned?

NOSONYXC63

yes... I have an OE tune... , this dyno run was done on a 95 degree 110% humid south florida day..

trapper

I think theres several of us that are watching for the numbers this puts down at the track. If it works well they may sell a few.

If it works well and the g/b price was around $1k...how many more would sell? Thers alot of cool parts competing for the same $$. If this flops....theres other choices...Good time to own a c63.

Sincity

When I met with C63 Guy earlier this summer, he thinks there might be some gains. I'll pick his brains when I see him tomorrow.

SonnyakaPig

Thanks for sharing your dyno results. Was that a 93 octane baseline run and 93 octane tune?

Just a tip, make sure your "after" dyno results are measured in STD with the same smoothing so you can get the closest comparison.

NOSONYXC63

My buddy owns the dyno so I can use it all the time...Thanks for the tip

SonnyakaPig

No problem.

That sounds like a cool situation. Good luck with the mod.

Sincity

Mike,

Is this a pre-production mock-up unit? Are you able to replicate the "ball" joint section of the OEM exhaust? I see that you could probably reduce some cost by reducing the amount of pre-bent mandrel pieces and welding by duplicating what GT Pro did with their pipes at the flange and primary section. Also, GT Pro also retains the factory mount/bracket at the primary section.

Sincity

Never got a reply back from FMU. Also, NOSONYXC63 went custom, anyone else have this setup to test?