Mine leaks here (see pic)

Don't need a smoke device to find the leaks (on mine)... you can feel the air puffing out by just holding your hand nearby.

 

Interesting...I'd not seen that model muffler...very different. You know...I'm not sure that some air entering there would really contribute much to the decel pop. The kind of exhaust leak more contributory to decel pop occurs at the head flange or at least closer to the hotter end of the head pipe as a general rule. Not impossible, just not as common on a design like the KLX.

 

DEP pipes are big in Europe, and just starting to catch on in the U.S. I was looking for something relatively quiet, that wouldn't melt the right rear turn signal on my '09 KLX (you know which one I'm talking about). Not many choices out there that fit that bill... which led me to the DEP. It's super lightweight, and sounds incredible. Nice bark to it. Company says 94-96 dB. It's an oblong shaped muffler, and the kick at the end directs the exhaust/noise to the rear, not up. Now I have to figure out what to put in the huge space left under the right number plate now that the huge cat is gone. I'm thinking I can easily fit a 32oz fuel bottle up in there... just not sure how safe that would be.

 

Looks like a two stroke silencer. I have removed smog equip on both the Klx250 and ZRX1200, both had similar setup. Neither bike pops all that much, both have jet kits, aftermarket exhaust and mixture screws tweaked. No idea why Rgoers still pops on decel, how did you seal the air intake on the head? Exhaust leak?