The Fazer 600 is great on track, I am off to Bedford on Monday the 15th, noise has never been an issue, I have a DB killer and never get higher then 90db. I have done 8 track days and have always had a fantastic time, it may not be the fastest on the straights but the brakes and cornering ability make up for it. I have plenty of my videos on YouTube (FZS 600 Bedford Autodrome track day 25th July 2016 Session 5)
I have changed the tyres to Pirelli Supercorsa's, dropped the front forks through the yokes by 40mm, made some foot peg risers, changed the front sprocket to 13 tooth and added a reverse race shift. My Fazer has 87,200 miles and still hits and indicated 135 on the Bedford back straight.
My advice is go for it, you will have some much fun, just remember to go at your own pace and it is not a race.