Just got back from a 4 day 3 night 903 mile trip on my '11 FLHTC. The mufflers sort of drove me nuts after all that time - just a touch too loud for all day running. They are the stock HARFLT1584/1688 muffs. For giggles I pulled them and put on a set of HARFLT1584's (no slash) off of a '07 FLHTCI. WOW what a diff - mucho quieter. Closed loop fuel inj sys seems to be doing its job - no coughs/lags/sputter/richness/etc. Seems quicker off the line but I'll bet it chokes a little earlier at interstate speeds loaded down since there is no free lunch. Will test that soon. Think it might over heat?

 

Check the part numbers for the '07 slipons and I think you will find they have cats in them. This is the one year that Harley put cats n the slipons. I have a set of CVO slipons from an '07 Road King CVO with cats in them that are pretty damn quiet. I bought the whole thing exhaust system off eBay in '08 or '09 and they sat in my garage for a few years. Then I put the system on my '01 RKC and was amazed at how quiet it was. When I got my '12 RGU I bought a set of '13 CVO slipons thinking they would be quiet too, but they are pretty loud. That is when I researched the part numbers and found out the '07 slipons had cats in them. I now run them on the RGU with de-cated head pipes because they are quite. The '13 slipons on on the '011 RKC that my son now rides.

If I could find a set of slipons that were as quiet I would use them, but so far no luck.

 

No cats in a 2007 road king mufflers.

 

If you are looking for a quiet system without giving up anything in terms of horse power and torque consider Fuel Moto's E-Series 2 into 1 full system. I also got tired of my ears ringing after a long day on the road. It's significantly quieter than the D&D Fat Cats I'm running on my Softail and 06 RK.

 

In 07, I believe the CVO bikes had cat in muffler and the international version of non-CVO touring bikes also did.

 

My 07 FLHTC had no cats.

 

My 07 had cats in the mufflers from factory. I put a set of 2011 mufflers on and it woke it up huge and my wife the first time I started it in the garage. Tee hee.

 

Start by wearing ear plugs on long trips! We've been told about the danger to our hearing since the 1970s. We are subjected top lots of noise while riding at speed for a long time.

 

The cats were in the 2006 CVO pipes. I had to core mine out.

 

I think the part number is 65913-06A