I just purchased a set of front hoosiers D12 Compound. $82 and change each. Rears I have been using the Tri-Trac tires and they seem to be good. Not sure on the compound, they are a little harder then the fronts.
Oh man, I did a full write-up about a year ago on the old 450rtech.com site.
I think it's all gone right now though.
Heres the difference in the stock plates on my old 05 compared to Barnett Dirt Digger clutch
The longer spring is the Barnett spring
I think the reason I found the site has something to do with you sending me the link to it on Facebook. ;) I'm pretty sure anyway. lol
You will have to look at your arms first.
If all of the mounts are the same, then they will not fit the oem ds450 arms because where the shock mounts the inside...
Depending on track conditions and and the size of track, you will need different tires.
10" rims all around. Less tire roll.
If you already have long travel arms, you could just put your stock shocks on to lower it.
Make sure your rear end is soft so your weight can transfer to the rear tires...