I have an 05 yfz 450 with an 07 crank and a ported and polished head, I recieved my new drd slip-on a couple of days ago. As soon as I pulled it out of the box I said (wow!). This thing looks great and it is built very well. The fit and ease of installation was great, it bolted right up. There were also new bolts and spacers supplied with the exhaust. It looks great on the bike, and has that deep throaty sound everyone is looking for but, not too loud. I have not rode the bike with this exhaust yet (due to the great weather we've been having) but, when I do I will write another review. So as of now I would reccomend this exhaust to anyone... Great work DRD.