I ran the PC pipe and stock silencer (bounced back and forth between the stock and shorty). I think the PC pipe smoothed the hit some, but I also ran a 50 tooth rear. You can also change the timing, just remove the timing cover, loosen the Phillips head screws (careful, they'll strip VERY easily), and adjust the timing within the 3 tick marks at the top. I know one shifts the hit UP in the powerband and one shifts the hit DOWN in the powerband, can't remember which though. I had a stiffer spring on the rear end (I'm 185 #'s) and added about 5 cc's of oil to the forks on stock springs, 50/50 mx and woods. I REALLY liked the KX in the woods, although the suspension was a little too stiff (I had it set up for big hits in mx/sx), but not unbearable and easily adjustable. The bike was VERY fast and had great bottom end. I had it for 2 years and never replaced a clutch (never needed to slip it). Brakes were awesome (I liked them much better than my new Honda's). I replaced the topend once a year (If you run a search, I've got pictures posted of my topend after over 100 hours...still looked really good!). I changed tranny fluid about once a month (riding at least once a week) using the cheapest Type F ATF I could find at WalMart. The only problems I had with the bike (and didn't encounter them until the same time I got rid of it, about a month or so ago) were linkage bearings were shot and seat foam broke at the curve just before the tank junction. A new SDG precovered tall seat was #1 on the list! Give the bike a chance, it's awesome!