Greetings.....can anyone enlighten me as to why my 2007 fatboy has different outlet diameters on the oem mufflers??

thanks

Gooday Muph, it's all to do with sound and noise emissions.

 

Google    " Harley Davidson Active Exhaust control "

 

https://www.google.com.au/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=harley%20davidson%20active%20exhaust%20control

To do with the 'Euro 4" noise regs we get by default in Australia

At certain road speeds / revs / gear the bike is actually a 2 into 1 system

By now most 2007's will have had the system "tuned out" with one of the race tuners , and /or physically removed by the owner

As soon as you fit any aftermarket exhaust it's gone anyways , both mufflers will have equal outlet diameter

Is your bike a recent used yank import ? Even then , "Aussie mufflers" will have been used to get it complied and past state rego

Even new bikes today still have that stupid system on them on most Softail and Dyna models

Ok peeps, I see the light now. Yes mine was first licenced in Oz. I just removed my V&H slip ons, just to loud for me. Found these OEM mufflers and fitted them a few weeks ago and just noticed the difference of the outlet diameters when cleaning the bike. Thanks for the replies. By the way, i seem to have more torque now. Before with the V&H mufflers the bike seemed to struggle some when going to 6th at anywhere between 80 and 90 but now no probs at all even at 80. Its quiet tho.
 

What you can do is source used Fatboy mufflers in the USA. 2007 to 2010 should do. 2007 Deuce had the same mufflers.

Easy enough to find them on US eBay

All other Softails the mufflers won't fit

Back in 2007 most US states did not have catalytic converters in the mufflers ( yours do for sure , it will say Euro catalyst on them !)

You'll have to do a part number search ( I used to know all the numbers but that was donkeys ago sorry !)

Those mufflers are a bit "louder" than Aussie spec mufflers , and perform better to boot ,both same outlet diameter

Yes mine have cats. I wonder if anyone has tried to drill out the cats?

Mate just quietly I wouldn't be riding in 6th gear at 80 or 90........ unless you're talking MPH

Yep, I hear ya, I'm just making a comparison. The bible does say minimum speed for 6th is 80kph tho. I'm just trying to get my head around this increase in torque after fitting the OEM cat mufflers.