I'm plannng on getting one in the near future, but was going to do the slip on that is a single, similar to the OEM or all the other aftermarket models. the shop I favor said to go with one of these since they are legal if you leave the DK in, and I should not need to put on a PC. I was interested in the Two Bros, but was told you should really get their juice box or a PC. I believe it was WelJo who recently commented that he was using a Yoshi and said he solved the backfiring problem with the??? air filter. I do not know if he did other mods though.
2009 Versys (Mine's Green)