I have a '07 FXDC.
It has EFI and catalytic converters. can't mount aftermarket exhaust without catalytic converter because that would
a) make the bike illegal to ride and it'd be immediately confiscated at the first police check.
b) it would mess up with the ECU parameters.

So, I'd like to modify the stock exhaust. I don't want it to be so free that, again, ignition parameters get screwed up, but I'd like it to be a little louder.

Is there any suggestion?

Looking into the muffler with a strong flashlight, you may easily see the baffle, with its small holes on its walls, and the blind bottom.
What if I drill a 1/4" hole in the baffle end?
Like this (ignore the dots: they are there as filler or the forum would clip the blanks)

SIDE CUTAWAY VIEW OF MUFFLER END
BEFORE MODIFICATION
....____________________________
./
|_______ _ _ _ _ _ <- baffle with holes in walls
.........................|
.........................| <- "blind" end
._______ _ _ _ _ _|
|
.\_____________________________


AFTER MODIFICATION
....____________________________
./
|_______ _ _ _ _ _ <- baffle with holes in walls and
.........................|_
......................... _ <- hole into baffle end
._______ _ _ _ _ _|
|
.\_____________________________


Would this make the pipe louder?
Do I risk something in terms of engine performance?

Thansk.

 

i can tell you , that by drilling the holes out equally on both sides of baffle
will increase power and five you a better sounding exhaust , i did it on my old nightster
do not drill thru the plug thats in the center of the baffle that will decrease the backpressure
essentially you want to keep the design but increase the flow, so by drilling or elongating
the holes both sides you just increased the flow and not altered the engineering

 

Thanks. How I take oput the baffle?
Is it on the shop manual?

 

Any change tothe exhaustwill change the sound AND the tuning of the bike. If you are concerned with the law any change the the stock system could be a violation though it's not likely you'd get caught if all you did was drill a hole in the baffle. If you are concerned with the engine running well you should have the bike dyno tuned after any mods to how the engine breathes. There is no way to alter the sound without altering the flow/back pressure.

Can you just do a teeny bit of modification? Sure, and a lots of guys do it with no noticed problems in how the bike runs.On the other hand you can not know how muchthat change haseffected the flow characteristics without using a dyno and a sniffer. You could create a lean condition that will cause over heating or blueing of the muffler or even engine damage. These late models are already tuned as lean as they can be just to pass EPA stuff. Feel lucky? Just be carefull & best wishes to you.

 

I say, if you can do it and if sounds good and feels good, than do it. You only live once!!

 

its a real pain in the *** depending on the style of muf. take a peice of round nylon( proper
dia as to fit inside baffle ) drill a thru hole thru it ( as a guide for hole saw ) get a proper size
hole drill 1/5/8 i think an and with the plug inserted in baffle , hand drill with hole saw
the weld that is atthe end of the pipe this weld has to sawed away to reveal the baffle
assembly. then elongate or drill out the 2nd side of holes after the plug . leave intact
the holes before the baffle plug. if you drill out the holes to .250 or .312
youll get better performance without screwing all the ecu / fule map **** up
BUT yur gone to have to get a fuel management system i use cobra but other works as well
unless you have acess to a machine shop like me ( im a machinist ) its just a lot easier
to buy aftermarket.
Ed

 

I modified my 07 softail fxst stock exhaust. I live in cali and my bike dosn't have a cc. I took a 3/8 inch od iron rod, about 4 feet long, sharpend to a point at one end. I stuck it up the muffler end at an angle, took a 5 pound hammer and pooked three holes in the side of the baffle, both mufflers. I had to wiggle it back and fourth to remove it, whick made the holes even bigger. If you do it you have to be careful not to try and poke a hole in the end plte of the baffle, too thick and will kill your back presure. I then went on a long ride and ran it at 100 mph to blow some stuffing out. Performs much better accross the rpm range, no detination and does not run hot. This is a temp fix until I remap and get some better pipes. I do know that a twin cam EFI will never sound like a single cam carbed bike, but its better than it was.

 

Putting holes into the converter can and will catch fire during a decel operation as the raw fuel is passing through the pellets. This will look like a fire works sparklers from the end of the pipe. I did this in a dyno room once......it was frighting.

 

I have a set of Screaming Eagles Mufflers for a 2011 CVO.
65583-11
65594-11
Can anyone tell me if there is any internal difference in these pipes other than on is for the left side and on for the Right? They are like brand new, and I really like the fat 4in dia. I know they are not loud, but I don't need the loudness.

Thanks,