I call BS on this. If you change the exhaust on any engine, you will have to change the mixture to suit (especially for a carb).

If four-stroke engines need back-pressure, why do the fastest engines out there run with no mufflers?

Backpressure for low end torque and drivability. Open exhaust for maximum high-end power.

Someone has posted here before.....

"Loud pipes save lives.....but apparently helmets don't"

Ride a Ducati...."Loud clutches save lives"

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

Did you even read that? It makes no sense. What in the hell does back pressure even do? It's the velocity of the exhaust leaving the the combustion chamber that promotes efficient cylinder filling and greater power. Not back pressure.

Inertia causes incoming fuel/air mixture to be pulled through the valve into the combustion chamber and right out the exhaust.

Proper back pressure then stuffs the good mixture back into the combustion chamber before the exhaust valve slams shut.

"Loud Pipes Are Loud"

Thank you, couldn't have explained it better myself.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

We live across the street from a drug & alcohol rehab center. Apparently everyone in there know someone with a Harley with straight pipes; all hours of the day and night, folks are coming and going out of the place. True to "I have a complex" nature, they need to tear-ass out of the drive and onto my street.

During college, a buddy and I bought a big Cadillac with a 472 and several exhaust leaks for $50. We took it out for a test run, and got pulled over for noise (and issued a ticket to boot). As we sat there waiting to the cop to finish writing out the citation, a gaggle of Harleys with straight pipes launched hard from a stoplight not 30 feet from us. My friend and I looked at each other dumbfounded as the cop didn't raise an eyebrow.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I find it a bit amusing that some of those 1 to 2 liter gasser bikes make far more noise than my 7 liter diesel 3/4 ton truck!

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

I guess I'll throw my 2 cents in here since I work at a Harley dealership and have done so for over 15 years. There is a fine line that is walked when it comes to making a bike run well with less restrictive mufflers and making it run like s@#t with mostly or completely open pipes. By far, bar none, the best setup for a v-twin motor is a two into one exhaust, if you want to improve the performance of the bike. The problem is most people don't like the look or sound of that setup so they go with whatever they've seen or heard which is usually crap when it comes to peformance. Drag pipes just plain suck and I laugh inside whenever I see them on a bike.

As far as noise goes, some motorcycle riders are digging their own graves by attracting way too much attention to themselves. The local and federal governments are getting lots of heat from people complaining about the noise. Keep riding those horribly loud bikes and see what big brother does about it!!! Let me thank you in advance for attracting undue attention to motorcycling.........and no, loud pipes DON'T save lives!!!

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1995 Toyota Pickup
2003 Suzuki Burgmann 400
2002 VW Passat 4Motion V6
1957 Aristocraft Torpedo Boat

He said!

I've got Screamin Eagle slash cuts on mine with the original crossover.
When I had it on the dyno a few years ago, I think he took some of the baffles out. That and richer fuel adjustments incresed HP by about 8%. Had more at the bottom and more at the top. Didn't sound too bad then. Gettin noiser now I've noticed.
(But it sounds like a Gold Wing compared to the guys I ride with)
Hey: "Sounds like a Gold Wing" Is that an oxymoron?

I am NOT running drag pipes on my Road King. I like my own hearing too much. They are Screaming Eagle pipes that were installed by the Harley Dealer before it rolled out of the showroom and the carb was re-jetted as applicable. It can be kept pretty quiet as long as you don't get too carried away on the throttle. Personally, I like the sound of a well tuned Harley but I also like the sound of old radial airplane engines and top fuel dragsters/funny cars making a good run (with ear plugs). As already mentioned I think the riders that run drag pipes are bringing the heat down on everybody.

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Jim

My Shovelhead had a clutch that was louder than any Ducati. At least the Duke had a cover over its dry clutch. Mine was just sitting on the side of the bike. Keep articles of clothing well away!

Don't know if it is louder than mine. I have no cover on mine and the basket is well worn. You should hear the tangs clack off the basket. I need to replace it.

__________________
'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

As an ex owner of R-1, I can tell you EXUP works like a charm. The back pressure is needed to create the velocity.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT

all I know is that a well tuned Triumph 650 with TT pipes makes a beautiful roar......