Well people feel it goes both ways.
Some say the stock header has enough restriction where a problem won't occur. Others say the cold air can get sucked back in and cause valve damage.
Been here a while and haven't read an evidence to confirm either good or bad,just a lot of speculation. I've had Stubby's on my bike and loved the look,just the sound did get to me after a while. They are loud while riding. So be prepared to deal with it. Easy enough to switch back if don't like. Cheap enough to give a try also. I didn't remove for mechanical reasons.