Exhaust help(Drill holes in muffler)

[BMWRT]

Hello all,

I had read a while back about one of you drilling holes in the rear of your muffler to allow a little more sound out. I have searched, but have not been able to locate the thread. There were photos also. Any help is greatly needed!!!

TIA,

[phoenixtexas]

TIA: I may have done the post you were looking for. I used to wrench airheads, and I would drill 8 1/8 holes in the stock knock-off cone from JCWhitney to let them breathe a little better and create less sooting in conjunction with a forward scoop and K&N filter on the airbox. The exhaust looked completely stock, but the sound was more resonant and not too loud, almost exactly like a Porsche. I would give the customer a set of polished stainless steel allen head sheet metal screws for the holes if they ever wanted to go back to totally stock.

I got on the forum and asked if anyone had ever tried this with a standard R1100R muffler and got one response. I am also installing a performance chip and larger air scoop. If worst comes to worst, I'll put on a new Vanderlinde, which I was thinking about anyway.

The way to drill is first make a template with an Avery label, scribing a circle right in the center of the flat part and then making 8 symetrical straight-line intersections. Drill there carefully with a small bit and then the 1/8 bit. Then peel the label off. It will look professional. If you don't like the result, you can always get the sheet metal screws mentioned above. Hope this helps. If you're interested, I'll let you know how it turns out since the stock R1100R cannister has a different shape than an airhead cone. I'll bet these small changes will eliminate sooting on the oilhead also. Phoenix

[DougM]

I did this to my R1150RS (same stock muffler as your RT). Sounded better than stock, but I eventually went with a ZTechnik pipe for less weight. Picture here (scroll down toward the end). (http://www.dougmosher.com/bmwr1150rs/Mods4.html#Bits) I'd sell my drilled exhaust if you're interested for $30 plus shipping (it has ~15k miles on it) if you wanted to try it out without having to drill your original.

[BMWRT]

Hey Phoenix and Doug,

I went ahead with the suggestion from Phoenix and it does sound better. Doug, it was your site I had seen some time back with your photo so that is where I stole the idea.

Thanks to both of you for your reply.
Andy

[phoenixtexas]

BMWRT: Let me know if the holes cut down on sooting. They have on mine as I figured, the main exhaust tube is turning light gray from black after about 300 miles.

[phoenixtexas]

Doug: I forget to include you in the post to Andy. Thanks for the offer, but I've already drilled mine.