G
Guest
·This has been done by some others, but I just tried this exhaust mod on my bike.
As opposed to Deb's internal exhaust mod, this approach simply drills a hole in the end plate of each exhaust. You can pick the hole size for your tuning and or sound desires. If you are concerned about TQ and tuning, it's probably best to start small and see the change before going bigger.
To do the mod, simply drill a hole in the end of each exhaust. The black end plate is a single flat sheet of metal. It will look like this when done:
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I marked the centers vertically, to mirror the center of the exhaust's exit tubes. Also - I drilled the holes with the pipes off the bike. If you want the drilled holes to line up, mark your centers with the pipes mounted so that you can line them up left to right.
Also, stealing Redbeard7's artwork for Deb's mod, here is what is happening inside the pipe:
![]()
The drilled hole will let some exhaust exit straight down the first pass of the exhaust. The remaining exhaust will exit in its normal path. I drilled my hole large enough to let an AFR probe from a dyno be inserted for later tuning. Since I have a TMax on the bike now, I know that my AFR mixture is still going to be the same with the additional holes as it was with the unmodified pipe.
To me, the sound is nice, not too loud but a bit throatier. And, if I don't like the performance change I'll just thread a couple of screws into the holes.
As opposed to Deb's internal exhaust mod, this approach simply drills a hole in the end plate of each exhaust. You can pick the hole size for your tuning and or sound desires. If you are concerned about TQ and tuning, it's probably best to start small and see the change before going bigger.
To do the mod, simply drill a hole in the end of each exhaust. The black end plate is a single flat sheet of metal. It will look like this when done:
I marked the centers vertically, to mirror the center of the exhaust's exit tubes. Also - I drilled the holes with the pipes off the bike. If you want the drilled holes to line up, mark your centers with the pipes mounted so that you can line them up left to right.
Also, stealing Redbeard7's artwork for Deb's mod, here is what is happening inside the pipe:
The drilled hole will let some exhaust exit straight down the first pass of the exhaust. The remaining exhaust will exit in its normal path. I drilled my hole large enough to let an AFR probe from a dyno be inserted for later tuning. Since I have a TMax on the bike now, I know that my AFR mixture is still going to be the same with the additional holes as it was with the unmodified pipe.
To me, the sound is nice, not too loud but a bit throatier. And, if I don't like the performance change I'll just thread a couple of screws into the holes.
Later,
