Originally Posted by Sincity

Thanks. Labor @ 6.0 is reasonable. I did a quick lookup on MOTORS and it is 2.5 per side.

Did Cory every tell you what the difference between K1 and K2 other than turning off the CEL for headers/high-flow cats?

Originally Posted by hotml350

Great review, clear and factual, a nice suprise on the forum, thanks for providing so much detail

Originally Posted by superlubricity

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.

Originally Posted by eashwar63

Did these headers connect to the stock cat pipes? I was searching for a pair of similar headers and the only ones I had found was from renntech which are 3.5k .I have ordered a pair of armytrix high flow decatted pipes, they are bolt on to the stock headers,so considering that I think these will fit the armytrix pipes. Should I consider this in the future? Did you have problems so far with these?Did it get louder after installing?
thank you 👍

Originally Posted by anomadtoo

Yes it’s normal. I attached the same headers. There’s no play after install don’t worry (I did).

Originally Posted by anomadtoo

Yes it’s normal. I attached the same headers. There’s no play after install don’t worry (I did).