My 2006 ac 400 fis auto 4x4 only has 150 miles on it and it is all stock down to the original Badlands 25x10x12's on rear and 25x8x12's on front, and i haven't had any of the problems i've read about tire's leaking, bead's braking from stock rim's, parking brake leaking down when left on for days at a time. No trouble with the stock shock bushing's cracking fender's,getting water on the belt; and a very long line of other complaint's on the cats. And i know i only have 150 miles on mine,but i haven't had any problem's so far i bought the quad to ride and enjoy for pleasure riding on trail's untill i get it broken in before doing any towing ! I've followed all the procedure's that came with my operator's manual, all the do's and don't's pertaining to my quad ! Thing's like not going over halve trottle untill breakin period, not to engauge diff.loc while moving, not exceeding 10 mpg with diff loc engauged, and i changed the oil and filter At 100 miles with Arctic Cat filter and the same oil i've used on every quad i've ever owned / i also cleaned the air filter, i've always used castrol GTX 10w40 winter and 20w50 summer ! I asked my dealer before changing oil brands, they told me it's fine and wouldn't void warrantee as long as i used the same oil i used on my honda's and suzuki's i've owned. I may not agree with everyone of bear's post's but i think he's right at least half of the time If not more! I'm not trying to suck up to bear And he's not paying me to do so, but with ( my own exsperious) over 20 yrs in the small engine repair bussiness from everything to lawn and garden tractor;s to motocycles and ATV's 2 and 4 stoke engine's i would be most likely to take his side on this issue about certain mods. If your ac shock bushing wore out after 5 miles maybe you and The 50+ rider's you spoke of who had the same issue, then maybe you and the other 50+ owner's got lemmon's ! Or the ac's were rode hard and put away wet , i hate to rain on anyone's parade but you can get lemmon's in anything you buy straight from the factory ! But i bought My cat and didn't plan on shelling out more money on mod's to give it more power and speed ! My 400 already goes faster than i care or dare go for use and age, i want to live as long as i can, if i wanted more power i would have bought one that had more power to start with; just make's more sense to me anyhow ! ..................williebee