Motorcycle Safety & Driveability: Drilling baffels, exhaust, pipe

Question
This was your response to a similar question.
"Answer
Hi Jim,

Thanks for the question. I'm glad to see you recognize the "silly machismo" of a loud exhaust. But lets just be guys about it and recognize that a nice bike with a solid exhaust note is a thing of beauty and enjoyment (that way I can also rationalize the Two Brothers Racing exhaust on my 1200 Bandit that sounds like a blown V8). OK?

The exhaust on the 1100ACE is indeed a nice piece of metal sculpture. Naturally, Honda had to make it sound like it does to pass DOT certification noise regs. And since that makes it just about silent, we have the booming market in aftermarket exhaust systems.

The thing is, Honda also went to great pains to make sure all the noise reduction did not rob a lot of power from the engine. That's one reason the exhaust is so big: there's a lot of volume inside the system to quell the sound while allowing the engine to breath a bit.

The thing most people notice when they install an "free breathing" (and much louder) exhaust system on a cruiser is a reduction in midrange power (also known as a "dip in the torque curve"). The reason is because of a loss of "back pressure" at certain RPM levels that the engine previously used as a "tuned pressure wave" to enhance torque. Take away that tuned exhaust, and it sounds better, but runs worse. It's also bad for the engine (the exhaust valves, mostly).

If you would like to modify the stock exhaust for a bit more music, it is common to "drill it out" as you suggest. This was common practice for standard and sport motorcycle owners when the DOT started quieting down bikes. But you have some things to consider. First, once you drill out the end caps, you really have no idea what it will sound like. It may sound like crap! A 1/4inch hole is pretty small, and if you look at aftermarket exhaust systems that sound good, you'll notice there are NO small holes at the end of the exhaust pipes. Just really big ones. So instead of getting that sweet "boom boom boom" sound you're after, you may get a "piff piff piff" or a tinny "bang bang bang" type of sound. And once the holes are drilled, there's no patching them up. Keep in mind that drilling out the pipes will change the tune of the engine and diminish performance, if only a little bit. You may also get some backfiring on trailing throttle (while slowing down with the throttle closed).

My advice is this: appease your macho tendencies with a new plasma TV or something, and leave your stock exhaust alone until you are ready to get a whole new system. Then get a system professionally installed, with a carburetor rejet for maximum performance. There are certainly a ton of great looking and great sounding systems out there to choose from. What you may find is that once your ego relaxes a bit, you may come to like the peace and QUIET of your stock system, especially on longer trips where a loud droning exhaust note is both irritating and fatiguing. And truth be told, the sound (to a bystander) of an ACE1100 throttling up is not bad: punchy but not so loud that grandma cringes at those "damn bikers".

Enjoy your new bike, and take a few long rides before you decide what to do with the exhaust. I understand your desire for a more robust exhaust note, but I'm afraid using the old sportbike tuners trick of drilling out the endcaps will leave you disappointed and with a slower bike. I'd wait until you can go with a whole new setup rather than modify the stock system.

Ride smart, have fun,

Bill Roberson"
My question is, I just bought a '07 Shadow Sabre new. Will the pipes get louder through time/ Or will I need to change or drill later?
Thanks
Greg

Answer
Caveat: the question's answer you quoted above was not mine, it must belong to some other expert.

The pipes on your Sabre will not get appreciably louder for the life of that bike, so if you're looking for something with a different exhaust note, it's time to start shopping aftermarket.

My advice is to find an Internet forum dedicated to the Shadows and ask around there for what systems people have used, how they like them, what they sound like, etc. Google search "discussion forum Shadow Sabre" and you'll probably turn up a dozen likely groups. Bear in mind that the Sabres from the 1980s were very different from the ones nowadays.

Pat