The opportunity to test out some log-style manifolds from PLM surfaced. I got them from a retailer on eBay so I could conduct a before/after dyno. I got a ridiculously good price on 'em (Please don't ask). That combined with my insatiable desire to tinker and analyze data was enough for me to dive into this little project. For reference, my Kleemann K1 ECU Tune/Dyno post is here.

To be clear, I wasn't expecting big gains. It is pretty obvious that the big bottle neck on the stock exhaust system is the restrictive primary cats. Bolting on a set of aftermarket manifolds isn't going to produce much power as the stock logs flow pretty good to begin with. If you are looking for the most power, Long Tube or Tri-Y headers are your answer. Anyhow, I told myself if I could pick up 15HP/15TQ to the wheels I'd be happy.

The added bonus for me is I'm not a "make my car sound loud as hell" kind of guy. I feel I'm getting too old for that. I also really like the sound of the stock exhaust as-is. Note: I have the right to change this opinion in the future if my mid-life crisis arrives sooner than expected and/or I begin to suffer from HP/TQ envy.

The Product:
Everything arrived well packaged. After opening up the box, the first thing I noticed was that the manifolds looked just like Kleemann K2 without the extended down pipe or high-flow cats. Quality was top-notch. The welds were clean, the flanges were huge. I was impressed. I wanted to get down to data so I busted out the calipers and the bathroom scale.

Stock manifolds weighed 6 lbs each. The stock collector/down pipe flange inside diameter is 1.85".
PLM manifolds weighed 3.5 lbs each. The PLM collector/down pipe flange inside diameter is 2.13".

OK, there was a little hope. They were lighter and there seems to be some room for power here. I even thought about how easy it would be to pick up a couple high-flow cats with a bigger inlet flanges to replace the restrictive primary cats. But of course, that would make things louder.

The Install:
The install took 6-hours. I had my local shop's tech do the work for me and at first things were a little rocky. He eventually dug-in and made quick work of the R&R. Everything fit flawlessly and there were no leaks.

Quick story. I was worried that the tech was going to get hung-up on the tight quarters. He actually called me with that concern after I dropped the car off. This same tech (never working on a C63 before) is going to be installing MHP long tubes on a friend's car next week. I called up my friend. He got on the phone with Andy at MHP and without hesitation Andy told him to have me call if I got stuck or had any questions. I wasn't even having MHP products installed on my car and he wanted to help me. Really cool guy. I called him up and he walked me through a couple tips and tricks and we even talked about some of our previous cars, etc. Kudos to you, Andy. That was mighty nice of you.

OK, enough of my rambling. Let's get to the data/results.

My Car:
2010 C63 AMG w/ Kleemann K1 ECU Tune (No Charcoal Filters)
2,104 Miles
92 Octane (Shell)

Conditions (on 2/19 & 2/20):
62-65 Degrees F
29.93 in-Hg
17-24% Humidity

Dyno:
Dynojet Model 424xLC2
All pulls done in 4th gear w/ SAE Correction Factor & Smoothing 5.

Results:
PLM Exhaust Manifolds (Best After Pull):
02/20/10 = 436.23 RWHP / 394.26 RWTQ

Stock Exhaust Manifolds (Before Pulls):
01/14/10 = 422.53 RWHP / 382.50 RWTQ
01/14/10 = 426.19 RWHP / 385.00 RWTQ
01/14/10 = 423.01 RWHP / 384.06 RWTQ
02/19/10 = 423.64 RWHP / No Torque Recorded (Wanted a more current baseline, tach sensor was flaky*)

Gains:
Power vs. 02/19 Dyno (Most recent baseline with same conditions but no torque)
+12.59 RWHP (Peak)
+20.95 RWHP @ 5700 RPM

Torque vs. 01/14 Baseline (Older baseline, but a pull with the closest curve to 2/19)
+11.78 RWTQ (Peak)
+15.86 RWTQ @ 4000 RPM

I'm hoping it will pick up a wee-little more power after it adapts a bit. We literally hopped on the dyno an hour after the install. When we were doing the after-install pulls, it kept making more each run. We stopped after 4 pulls and the peak HP never went down (425.98, 429.06, 433.90 and 436.23). I'll be back in a week (Seattle Dyno Day) for some more dyno time. I've already logged 25-pulls in 2,200 miles since getting the car.

If you are looking for a few extra ponies and do not want to increase the noise level/exhaust tone of your car, these manifolds are a great choice.

Graphs/photos below. I hope this was helpful.




















*HELPFUL DYNOJET TIP: If your Dynojet Operator can not get a RPM/Torque reading there is a solution. Make sure they use the single/primary wire tach pickup and the red wire going to the coil pack. You get a perfect tach measurement everytime. My dyno operator was using a different pickup sensor previously that pulled the signal from the entire wire budle. We often got interference and bad data. Using the single/primary wire pickup will give you RPM/Torque everytime.

 

How much did they cost you?

 

A ridiculously good price. I edited the first post. I really have no idea what PLM is going to sell these for. Their auction had the price listed at $2K.

 

Great write-up! Results look good, too!

Did they include new gaskets or reuse the old ones since your car is "practically new?"

And your car won't have to be "loud as hell" with LTs--just simply cruise or leave your car at idle and you won't even notice the difference.

Stupid tach-sensor.

 

Shall I start the bidding at $1? Just kidding.

 

Inline . . .

 

Great writeup. PLM is asking too much money for these shortys. For a few hundred more, I can go K2 with the higher-flowing cats. But you did mention the noise factor.

 

Thank you.

 

If noise is a concern then I would remind you that a K2 fitted car with the secondary cats RETAINED is probably not going to be louder than your tolerance threshold. My car got louder with the cat delete than it did going from stock to K2.

 

Cool. Thanks for sharing your experience.

 

Do you remember the gains from K1 to K2? If the gains are similiar to the 20WHP these shortys give, then I suppose labor would be a little cheaper since you do not need to cut out and install the high-flow cats.

 

For me, upgrading K1 to K2 19WHP and 11WTQ.

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

 

Tks.

 

Can you post a picture or 2 of the headers installed with the stock primary cats? Any sound bites with a stck C63 versus your car and the headers?

Thanks

 

These manifolds are direct replacements for the stock ones. The sound is just like stock. No noticeable change in tone or volume.

They replace #1 and bolt on to #3 or #4.

 

nice report thank you

 

Really informative writeup, thx. For this type of header these certainly look good...

 

What were the installation tips? The driver side looks really tight.

 

I am real disappointed because I tried to setup a time to see the Kleemann headers installed and get a before and after feel of the car in Houston, but last week there was some sort of screw up. I want to see a set installed with factory cats and get before and after test (dyno or street). I don't want to take someone's word for it. If someone would show pictures of before and after on a tuned C63 of header only installation and dyno test--I plan to order these headers.

 

By "pictures," do you mean pictures of the headers installed on the car? If these are shorty headers you're referring to (and the Kleemann ones are), then it'll be very difficult to see a picture of them installed on the car because it'll be all the way up in the tight engine bay.

As for taking someone's word, I agree that it's best to experience it on your own; but the next best thing is what's posted in this thread--a before and after dyno of a car using the exact same dyno in very similar conditions only 1 month apart. Can't argue with that data.

 

Thanks.
The Kleemann "headers" will not bolt on to the factory cats. You would have to install the Kleemann cats.



I also did a "day before pull" just to make sure the power was inline with the runs from the 14th.

I'm a bit dyno-obsessed right now.

 

It seems like the gains are about the same but difference is K2 has high flow cats...so what if you were to change your primary cats to high flow cats and use these headers...suspect mroe gains than K2

 

I'm guessing it would be very close. These are only "worth it" if the price is very good like $1k or less. Otherwise, stick with K2 since the asking price of the PLM's is $2k .

Overbudget has a set of VRP shorties. I forget how much power those made.

 

Superlubricity: Not sure if I missed it, but are you still on K1 tune? If so, no CEL since you are simply replacing the manifolds?

 

K1 Tune. No reason for a CEL to go off.

Look at the first dyno graph. AFR is identical before/after.