Hello everybody, it's been awhile, but I finally got a new (to me) bike. It is a 2009 YZ450F SE and it still has the stock exhaust. 6 hours on the bike. I found a great deal on a Leo Vince Full Ti system but it is for an 07. Leo vince customer support says that the 2007 and 2009 systems are incompatible due to the different header openings? True? Does this kid know what he's talking about. I did look a the schematics, and indeed it appears that the the header pipes on the Leo Vince systems have differing diameters. I guess what I want to know is if the schematics show the smaller 06 header flange having a 43mm opening (https://www.leovinceusa.com/schematics/large/DT-3678C.pdf), and the 09 having a 47mm opening (https://www.leovinceusa.com/schematics/large/DT-3660.pdf) what does that mean compatibility wise, and how come other companies don't note it. The flanges have the same width to bolt holes of 66mm. So, the head on the 09 is actually wider? Can I run the pipe with the smaller flange? If so, what problems am I asking for? Some of the aftermarket companies don't even sell a different aftermarket header for these years? This has all got me really wondering, is Leo Vince really on their game more than everyone else? or is the kid smoking crack and should I swoop in and pick up this exhaust for 1/2 price?