Rasta, That's how early auto and motorcycle racers got the edge..... "modify"
trial and error, and how much will it cost and what do I need to beat that guy in first place.
Keep trying new things, sounds like that new exhaust is working for you, but make sure you have a good seal where it mounts to the head (exhaust port).
That has alot to do with overall performance. There are alot of "tweeks" to do to bikes
without paying big bucks to repair shops and performance kits and it can be all found in this forum, it's helped me alot and it's FREE.
gimmiejimmie