check out the MOMO shift knob, i kno people with 4eat's that have no problem with them. Make sure any shift knob you choose is for autmoatic and not manual, then i think it defientely will not fit. Shop around for the Momo shift knob, some sites have em for an absurd price, but others have em pretty well priced. Counter clock wise off, clock wise back on for the shift knob.
subaruwrxparts.com is good stuff, ive ordered the momo shift knob, and a bunch of other things, actually a lot of things, they have great prices, quality service, and very fast shipping, dont think twice on ordering from them, scooby dude is nuts $200, he thinks he has gold because it says "momo" on it.