09 Ultra classic. I bought this bike a few years ago and wasn't happy with the stock slip on sound. I bought some slip on on-
Line...like the sound much better! My question is, now it pops n farts when I'm slowing down, never did that before??
Didn't use any sealer etc...juse tightened up the Clamp? Did I forget to do something?

 

As your exhaust gasses exit faster and they have still a very high temp, this makes them react with the surrounding O2 in the air.
You need to increase your decel setting to inject a bit more fuel. This will prevent the exhaust gasses from "popping"

 

It's common folk-lore that we can change certain things like mufflers, without retuning the bike to compensate. That is not always the case, as you may have found. By all means check that you don't have any leaks, either in the induction side or exhaust, otherwise look to retune your bike. You may be pleasantly surprised how much better it can ride!

 

Get a tuner and tune the bike...

 

My bike did the same thing now that the exhaust is open and free flowing.The FP3 tuner got rid of my decel popping and gave it a bump in Power.

 

it doesnt hurt anything, I like the popping and burping because it scares sockermoms in minivans and little kids.

 

yep, the lean out or unburned fuel collects in the exh till there is enough to ignite. so that tells me hd does not cut fuel off on decel till under a certain rpm, which if it did, the problem would not be there.