Always had good luck with the ct cylinders, I prefer them to any of the esr stuff My wifes bike has a ct310 non pv motor, LRD adj pipe, 39 pwk, moto tasinarri cage. and it absolutely rips. Taken down lots of 330,350 even a few 370pvs with it. It takes a built 500cc or bigger thumper to outrun it. Makes power all the way thru the rpm range. Most esr stuff i have rode is like a lightswitch either on or off the power. I had a set of ASR +2 arms on my last 250r race bike and they were very beefy. I would buy those, ive damaged a few lonestar arms over the years, but the asrs seem stronger.