what to look out for on a used S/C?
 

I found a top swap kit for 300 bucks. says it came off an 02 with 100k+ miles
what do i have to watch out for when buying a used supercharger?
what about the head and intake?
I have an 05 120k will this fit?

Make sure the coating on the rotors is still intact.

Make sure the coupler has no play in it.

Try to make sure the heads aren't cracked

Yours will work. mill the heads to make sure they fit right. While your at it do some work on intake. Some shops will redo internals of the M90 so You can look into that. Also Your car is non s/c so drop the boost a bit Cus you may get knock unless you drop the compression. But thats just me being overly cautious.

he said the intake is machined so o shouldn't have to worry about that. How much should milling cost? What if sc.is in bad shape is it worth getting for a rebuild?

with how cheap they are, i don't think it is worth a rebuild.