LOwer
THE best way to lower in yor situation is to go to a very low profile tire, the lower the betteer an dyou may even find that a slightly narrower tire with the lower profile will also help. Not only will this aid in lowering the seat height but aid, by changing the geometry of the bike and giving you better top end stability. I would recommend that you remove the rear fender hanging down like a drag cheut and I'm sure that you have removed the turn signals prior to running it...Take the gas can and only put what you need in the tank for each run, and get rid of everything on the bike that you don't have to have like centerstand, mufflers...I think that by going to a lower profile and even a slightly narrower tire you will get much better times than stock...Let me know, but I'll bet you a cup of coffee!