I had my OEM exhaust manifolds put back on my vehicle, but before they did so I requested a before/after dyno. I lost on average 11 whp and 9 wtq from about 2700 rpm to 5900 rpm, and my biggest losses were between 3500 and 4800 rpm (I'm guessing you guys call that the midrange) losing about 18 whp and 14 wtq. So I guess for the guys who wonder if headers do anything for our cars that answers the question. Full disclosure: my car is not stock so the numbers may be a bit exaggerated. I do have the Motordyne lower plenum and plenum spacer along with JWT cams, so the car may have benefitted from better breathing with the DC Sports in a way that the factory hardware may not. I have no idea what kind of power the headers would have made if it were the only modification, as in my previous posts I dynoed all the parts together. I hope this helps!

 

Any plans to adjust the tune?

 

Why go back to stock?

I bet the cams are what makes the difference.

 

The power difference was after we already re-tuned the car with the factory manifolds. It was the best we could get. I went back to stock because I was trying to figure out if I had header ticking or if it was something else. Unfortunately it's inconclusive so far. What a waste!

 

great example of how "it's the combination of mods that works"...

For years ppl bolt something on then post that it doesn't work.

Question is - now that you know the headers do work with your configuration, are you going to re-install... what a pita to go through - but hopefully you'll figure out what you were after...

 

Maybe when I receive my tax refund lol. We were trying to figure out my car's "ticking" because it started shortly after installation of the headers and cams, and everyone assured me camshafts are silent so they all suspected the thinner header walls was responsible. My car sounds a little bit like a quieter diesel as the RPMs climb but no one could find a problem with the vehicle. If you guys disagree and think it's harmless and normal from my headers or not related to my headers then maybe I'll put them back on (and hopefully someone else suggests a new source for the sound). At the moment I don't hear the sound, or it's at least less noticeable so I'm not quite sure if it's fixed or not. On the bright side, I finally paid off the car and the title arrived today. Awesome!

 

same thing happened to me after cams... it's loose valve lash (on mine)... I posted a thread with vid quite a while back...

 

just go by a meinekke shop they will tell you the problem for free