The new HMF Comp series slip-on it one of the best all around slip-ons from what I hear. Combined with a tuner, you should be quicker off the start and all the way through the powerband. Not real sure on top end, but low and mid should be better.
The programmer is what's really going to make the difference not the slipon. A full exhaust yields more noticeable difference but is more expensive. A slipon by itself is just going to make it sou.d better imo
If you don't go with a programmer you won't notice anything more than sound. Even with the programmer it's not like you are going to go from an even race to destroying someone. With such a small increase it's still going to come down to who got the better launch or who's the better rider every time
i recently added a slip on. no difference other than loud. then added a tuner. there was a noticeable difference but not day and night. but is still faster. little $ little faster...lotta $ lotta faster
You are going to want to go with the EHS programmer over something like the FMF or HMF programmers. Eric has done much more work with the XX and has way better maps. And I've found out the hard way that you really get what you pay for when it comes to performance. You are better off waiting and saving up to do it right once than go the cheap route and end up unhappy and redoing it
I would just leave the exhaust stock until you have the money for a full system. I contemplated the same thing when I first bought mine. Glad I didn't just buy a slip on. If your set on going that route find a FMF slip on so later down the road you can add the powerbomb.