I took the advice from this forum when I put a Slip-on exhaust on my 1999 Curvy e.g make sure I cut a decent distance from the join.
I used some of the information from this post by
Skivvie T
http://forums.sv650.org/showthread.php?t=227836
It has not affected the engine's performance.Perfect plug colour and once I'd ran some Redx Through the fuel and balanced my carbs I now get over 150+ miles before my Low fuel warning comes on which is fine by me for my weight <175 Lbs