Hlebo Bros suspension. I wouldn't bother with the 150R setup unless you want coolness. I'd bet that if you did the revalve for $200 (I'd keep the stock rear spring), and .40- .42 straight rate Cannon springs with the Hlebo damping rod mod, you'd love it. Like I said-- these mods have got me over anything the motor would propel the bike over. I race mine in the pit/play bike races, and I don't want to be that guy that wins the races b/c of my ride. I leave the damn thing showroom stock, other than pulling the baffle outta the exhuast, and the Hlebo mods to the stock suspension. Like I said-- I like to just enjoy the bike for what it is, and it's perfect for the AC mini track where it spends most of its' time.
If you DO do the 150R suspension mods, ya better limit the travel somehow to 9.5 inches unless you want to bury the cases in the dirt landing from jumps. The 150F has about 10.5 inches of ground clearance at the cases, and 150R suspension has almost 11 inches of travel.... soooo when ya do the math..... yep. I may mod out my other 150F, but ideally, you want to be able to race an $800- $1000 bike in the pit/play bike races, or nobody will want to show up. Ya start racing expensive and fully built bikes, and nobody wants to come race. That's why I just race a cheapo stock bike, and ride it like I stole it! --L*64