PLM Header Review
 

So, figured I'd make a new thread to do my own review of the PLM header. Lets keep the bullshit out of this thread. I'm aware its a replica/knockoff or whatever you want to call it of a nameless header. There is another thread full of that so any comments please direct towards there.

I was going to get something like a Tomei, an OFH or maybe something else if it showed up second hand but when I saw the PLM thread pop up and that someone submitted an offer for 375 and it went through I figured what the hell. Ended up getting it for $390 (that was the offer that was accepted on ebay)

The header looks good, the welds are decent. My two biggest complaints off the bat looking at it is that the wall is rather thin compared to other headers/exhaust components I've seen and the fact that the inside of the flanges are not welded just the outsides. I don't know what this does as far as efficiency goes or if its just a thing companies do to make it look better aesthetically but either way it just looks cheaper.

The install was pretty straight forward, all the needed hardware is there. Everything fit perfect without having to **** with anything, as others have said the dipstick tube needs to be removed in order to install this but its no big deal.

They supply a plug for the stock intake resonator removal and a zip tie for the fan harness to move them out of the way.

My biggest issue was the flange for the overpipe. This comes in 3" so unless you have a 3" overpipe you will need to do something along the lines of KoolBRZ which I copied in that i used a 3" and 2.5" exhaust gasket where the header meets the overpipe. This is not ideal, nor is it efficient but aside from disrupting the smoothness of the exhaust gases the rest of my exhaust is smaller anyways so it should not matter THAT MUCH.

OH, also there is one bolt on the passenger side header flange thats a pain in the ass, I had to use an open ended wrench to tighten it, I could not get anything else in there to tighten it.

Now onto the sound:

I have a TRD exhaust, still have the stock overpipe and front pipe. When starting up on a cold start it is a bit louder. Once it quiets down its pretty close to what my TRD sounded like Before.

When driving around town there is a bit of drone in the lower RPM range, not sure if its much louder outside of the car but inside there is deff some drone.

There is also a very metallic tinny/raspy sound in the lower RPM range till about 4-5k RPM. I think this is attributed to the thinner walls of the header. I can live with it but I don't much care for it. I don't think a resonator will help with this because its clearly from the header itself. From behind the car there is no tinny/raspy sound. I thought maybe it was an exhaust leak, but getting under the car and having my wife rev it, it doesn't sound like a leak anywhere. I'll need to do some logging here when I find my OBD adapter to watch the fuel trims in real time.

When you step on it, well it screams. Doing a second and 3rd gear pull up to redline it sounds amazing IMO. It is very loud and aggressive sounding. Had a friend behind me last night and he said he loves how it sounds when I step on it and that he did not notice any "rasp/tinny" noises. Just a nice high scream coming from the exhaust pipes.


Performance:

I did not put a tune on the car for the first few days, I figured I'd drive around and make sure everything was good before I loaded the OFT tune up. Now even without a tune it feels like the car actually wanted to pull all the way up to redline. it did not seem much faster but I could feel the car still pulling past 6k or so where it would always feel like it started to level off to me.

I finally put the OFT Stage 2 93 El tune on the car with my OpenPort the other night and i can definitely feel the difference now. It's by no means a rocket ship but it feel like from about 3-3.5k RPM up it just pulls. I can still feel the lack of power if im in say second from 2-3.5k but past that you can feel the car just pulling. No longer does it make a lot of noise, the RPM gauge moves but you feel like you're along for the ride, it actually feels like the car is pulling you now.



Overall I think its a get what you pay for type of thing. Is it just as good as name brand higher priced headers? Well from a quality standpoint no. From a performance standpoint, not I or anyone else can say without independent dyno numbers in a controlled environment. It without a doubt makes the car perform better, pull harder and sound pretty damn awesome when your booting it but its definitely not the cream of the crop as far as exhaust components are concerned.

My biggest complaint with this header, and the reason I may end up shelling out the money for a more expsensive high quality one is the raspy/Tinny sound in the lower RPM range when you're just cruising around. I don't care for it, however I'm going to get a good resonated front pipe and see if that helps however I don't have much hope as I said its clearly coming from the header and not the back of the exhaust.

However, it will server its purpose and do a pretty decent job until I have the spare cash to throw at a better quality header.

Heres a quick video I took on my way to the store. You can hear the "rasp" sound when I step on the gas, its probably most noticeable when im going over the bridge.

Honestly it sounds more apparent in person. My friend who was driving around with me yesterday said he did not really notice it, however it seems pretty loud to me.

[ame="https://www.youtube.com/watch?v=tgkcI2Za1Oo"]PLM header rasp - YouTube[/ame]

Yeah, I think I was the last one to buy it for $375 lol

Is there an overpipe that will fit that flange and then connect to a Tomei Titanium straight pipe? I have been searching everywhere for info on this setup and I am failing miserably. I am also having a terrible time finding a titanium mid pipe to fit up to my titanium axle back too. But thats a totally different story... Thanks in advance.

Any 3" overpipe.

Update: I just ordered some GrimmSpeed gaskets for the header flanges. I'm thinking the gaskets used (ones that came with the header and yes I know i know cheap gaskets bla bla but ive used cheaper gaskets on other cars in the past without issue) are not sealing properly. Reason I'm starting to think this is that when the engine is first warming up the "raspy/tinny sound" is much worse and as the car gets up to operating temperature it seems much less noticeable. So i'm sort of thinking that when the gaskets heat up they are expanding and sealing better.

Who knows, either way I'll know for sure once I get those grimspeeds on. I'll keep everyone updated.

Thanks for the update and let us know the numbers after the tune.


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I won't be getting a custom tune. I'll continue to run the OTS from openflash. I have 0 desire to spend the money to have a custom tune made to squeeze out the extra few HP from fine tuning.

However I will update as far as the gaskets are concerned once I get those in.

Any updates?
I have a shop around here that'll do dyno pulls for $100, it would kill me to not know what my car was putting down.

Recommendations, theories, and words of wisdom from KoolBRZ
 

As a tuner who used the PLM header for tuning, I know some of what you're going through. The exhaust flow through the PLM header is VERY different than the EL headers used to make the OFT tunes. My car is an AT, and would never have as much low-end torque with the PLM header, as it has with the Tomei Expreme, but an MT doesn't need as much, since the gearing is so different. The PLM has a lot more open space in the primaries, and that makes it a lot harder to tune than the Expreme UEL, which has smaller, longer primaries. I finally decided it was a better header for MT cars than AT cars and got a Tomei Expreme UEL instead.

I was wrong. It isn't about whether the header is EL or UEL for MT or AT, it's all about the size and length of the headers primaries. That determines where in the powerband peak power will be. AT's normally need that peak to be lower in the powerband, while MT's normally need it higher. Since each header's primaries are different in size, shape, and length, the tune's AVCS tables need to tuned for the header, and there is a simple, specific, way to do it, by ear.

My theory is this, when the AVCS is tuned properly, it will sound louder throughout the powerband, and will sound evenly throughout the powerband. This is an example of an AVCS Intake table. It is tuned for use with a Phantom SC, so it is less overlap than an NA tune would use, but you can see that it is an even, consistent change throughout the table. This is what is needed to get the most power from the the entire powerband. The tinny sound you are hearing is because the AVCS timing is off in the lower rpms, there should be more overlap there, making the sound more boomy, more like a trombone than a trumpet.
AVCS controls the speed of the airflow, and depending on the speed of the flow, your engine will burn more or less efficiently. I use my OFT to constantly monitor Engine Load while I drive. This gives me an indication of how efficiently I am burning my fuel. The sound is an even better indication. It should sound almost quiet at idle, yet get that trombone sound with the slightest acceleration, and keep it all the way to redline.

Almost every header will sound like this with no cat. Local cars running Tomei are no different.