Yes I had the same 2 times. Did u change your exhaust which most probably cause this problem. Removal of cat.converter changes the air balance as far as I know and sometimes this happens. I had 2 bros complete system.
Sound will change for sure, at the end you are removing one part from inside. Also there will come some blue fire and some little explosions while deceleration.
Also easier way to check ABS is on the wheels. Both wheels should have ABS pulsar ring in the middle, they look like in this link
http://2.bp.blogspot.com/-amqyLDzp-do/Uf5GIiS-enI/AAAAAAAAAZc/BxYPdx25tQw/s1600/how-motorcycle-abs-works-64330_2.jpg
You should know that non of the frame sliders will protect the bike or you if you are not falling while you stoped or have a very low speed (may be upto like 25km/h).