EDIT: This is what happens when you mismatch exhaust components. The DG slipons WILL NOT mate properly to a performance header. I "forced" the issue and ended up with predictably terrible results. DG's are designed to perfectly replace the stock muffler, and slip right into the stock headers' seal. Any slipon that requires the removal of the seal in the stock headers' bell in order to slide in, will fit the FMF headers perfectly.


Run 002 is DG-R and stock header.
Run 005 is DG-R and Megabomb.

Click on the thumbnails for best quality.

The changeover from stock to megabomb was done with bike on dyno. These runs are only minutes apart.


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brad1_zpsb566f5ba.jpg?t=1396485113

 

This seems pretty definitive to me. I should go back to all those threads bashing the stock header saying its flow is so inadequate...

 

What causes those dips around 7900rpm with the stock header?
The Megabomb curves are certainly smoother but hardly any real gain.

 

I'm recovering from the disappointment. I kinda went into shock at the dyno shop and didn't ask all the questions I should have. I will ask about the dips when I recover.
In the meantime, what the hell is with the AFR going richer with the megabomb? The tuner said it must be adding back pressure to cause that....? WTF!

 

i mentioned before in my megabomb review that the megabomb didn't actually increase power...what it did was increase throttle response and smooth out sudden throttle release (engine braking) and quick turn of throttle again...it allows you to decelerate accelerate quicker and smoother

 

Ok, some more data.

I.D. of the megabomb at connection - 1.457"
O.D of nipple on DG-R that slides into connection - 1.25"
I.D. of DG-R at the radiused end of the nipple - the most restrictive point of the entire system to exhaust flow - 1.125"

Obviously the nipple and I.D. on the DG-R is quite smaller and restrictive than what could be achieved with a thin wall nipple with an O.D. closer to 1.457". As is is now, the gases are running through a 1.457 pipe and meeting a 1.125 pipe.

The DG-R is a tight fit to the stock header. FMF claims the powercore 4 is also designed to fit the stock header - so what the hell! And my megabomb is actual FMF. I guess FMF expects us to have custom work done on any slip-on to fit the megabomb correctly. I had to wrap the nipple on the DG-R with muffler tape until it sealed with the megabomb.

 

I have a powercore4 and a powerbomb, I have posted many times that from my experience it didn't add overall power but the addition of the powerbomb added a small amount of grunt or torque right off idle. More than anything on my bike it moved the torque curve some but that was it. I never felt it had any real world affect on the jetting. I'm not sure by mixing and matching your pieces you got results that seem meaningful. I can't get anyone in this town to dyno my bike with the knobbies on it. So my results don't mean much either. I did just get the Bill Blue big bore so I have good things in my near future. It might be cool to put a street tire on it and get it dyno'ed with stage two type mods and 351cc's.

 

"In the meantime, what the hell is with the AFR going richer with the megabomb? "

You have the data. Looks like #128 is in order. Keep us posted. Thanks For your contributions to the knowledge base.

 

Or the megabomb could be more effective/pulling harder on the jetting in that rpm range richening up the afr and throwing off the hp results at the same time?

 

But really guys, even if it is a little rich, I don't think that will account to a greater increase in horsepower, maybe increase from to .05 a horsepower instead of .03 after rejet? Hahaha


Klxster, I understand that you are in shock, I would be livid, I personally expected at least a hp and a smoother power curve. But just think because of you people don't have to spend their money on something that is of minimal gain. Thank you