How to modify your stock XT660X exhaust

**Metal Doctor** · 27th November 2012, 10:48

it seems there are alot of guys out there in interweb land asking about modifiying standard exhaust mufflers.

i had the chance to modify a pair on a 2005 XT660X and thought i would share it if anyone wanted to have a go themselfs.

Now i want to make it clear that this will make the bike much much louder and it will need to be tuned to the new exhaust. The bike that these mufflers came of had already had the airbox modifided and changed to a hi flow filter, and the fueling had been changed, but it still may need more tuning so it performs at its best.

This is not a straight forward job and knowledge of welding and fabrication is essential.

What tools you will need:
a grinder and cut off wheel and a grinding wheel
a die grinder and burs or a dremmel
a welding set, preferably a TIG welder and stainless steel filler rod
a hammer and a long drift
a permanent marker

a short length (1-2 meters) of 57mm perforated exhaust tube
exhaust repacking wool
high temp silicon

First remove the mufflers from the bike and remove the heat shields off the mufflers

1. remove the muffler tip by drilling out the rivets.
2. use a permanent marker to mark lines on the muffler where it starts to taper at the bottom, these are your orientation lines that you will use to re-align the two parts back together (this is very important)
3. cut the muffler in two where it starts to taper, cut through the center of the weld.
4. grind off the small weld at the end cap.
5. inside the tapered lower part of the exhaust that you've cut in two, there is a small honeycombe can, using a die grinder or dremmel cut this out.
6. using the long drift, hammer out the internal part of the muffler, this will only go one way, and it will only come out if you have fully ground off the weld at the end cap. hammer in the direction of the exhaust gasses.
7. remove the wire wool that is left inside.
8. cut off the exhaust end cap from around the small tail pipe, cut a hole no bigger than 57mm. i used my tig torch to do this.
9 measure the length of perf tube needed and the offset angle piece you will have to make so the perf tube meets the origional exhaust tube. you will see tis in the tapered part of the muffler where the honeycomb can was removed, the pipe is not in the center. weld the end cap to one end of the perf tube and the angle pieces to the other end.
10. wrap exhaust packing wool around the exhaust and hold it in position with tape, apply silicon to the end of the packing wool (ie; follow the instructions on the wool packaging)
11. carefully push the wrapped perf tube all the way into the empty muffler.
12. making sure your angled piece meets up with the origional exhaust tube and your orientation lines are lined up correctly weld the two parts of the muffler back together, then weld the end cap in place.
13. rivet back on th muffler tip
14. fit the exhausts back on to the bike and the heat shields to the exhausts.
15. Fire the beast up and listen to the thunder you have created!!!!!!

**hypoboang** · 18th May 2013, 14:39

good mod my friend. these bikes are shockingly quiet standard. Your way looks easier than the way I did it (I posted pics on xt660.com).

I removed the end caps and chisled out the internal plates leaving the large tube inside. When I finally made it to the cats I used a long tapered stainless rod to break up the cats into pieces. used a large hammer. then replaced the whole unit with the perforated pipe the same way you've done. At first I just replaced the end caps temporarily as I wasnt near a welder. that was loud! sounded heaps better with the perforated pipe and some wrapping.

yes indeed it does sound great and makes the xt sound as it should! a real thumper!

love your work mate!

**enzedone** · 24th May 2013, 17:09

No offence, but I purchased a set of titanium cans and link pipes for what it cost to do that procedure. As I bought that XT. New pipes removed another 7kg off those guttered ones. They sound and look better. Shop around, you can get some good deals overseas. Silences (even with link pipes) incur no duty from Customs, as they are not a full system. There will be GST and Biosecurity fees though, but still worth it.