I'm sure you can take off the stock stem, place the round part on a table and roll it. If it wobbles, its bent. IF not then you should be fine.
Also, I was talking to Nate Walsh the other day. I actually just got my set of Walsh FLow arms and should be getting my stem soon for my 09 SX thats ordered. The walsh stocker is 0 I believe and the Anti Vibe is 0 + for the Clamp I believe.
Nate was telling me that they can't pc them due to clearance issues being soo tight, so they are nickel plate ONLY. Thats kind of a bummer, but once I get mine I'm going to work on a way to figure out how to run it with PC...
Just my .02
its because of the way the stem bushuing slides over the top of the stem, you could powdercoat it from the busing down.