Hello everyone

Since i bought the bike a couple of month back, this one came with dual scorpion cans, since the day 1 I notice a loud bang every time i'm shifting gears.

I check all the unions of the pipe, and seal them with some holst paste, in some parts it was leaking a little. But the noise is still there.

The weird thing is that is only while shifting and at 3-3.5k rpm, below and above that is not reproducible the bang. I checked the cans and doesn't look like maybe any crack on any of them.

Anyone may have some information about what could be the route of this? is normal? i know of some bike that use to 'fart' but i don't know if the xt660z is one of them

King Regards