I noticed when I've been shifting into 5th above 3000 rpm, I get a slight "jiggle" in the shifter, and it makes a little noise. Not exactly a grinding noise, and it goes into 5th fine. Is this a synchro thing or what? Any ideas?

 

is prolly u 5th gear syncro's givin up... alot of prelude owners have that problem...

go to a GM dealer n buy some syncromesh < is a type of tranny oil... it does magic to our 5th gen tranny...

 

This is a known issue for the 5th gen preludes. They don't have an official recall on the tranny, but they do have a service notice. You could search the web a little harder and probably find the number.

I had the same exact problem. To truly fix it, the fifth gear needs to be replaced along with the shift fork. After a little haggling with a few people, I was able to have Honda pay for 75% of the cost, since it is a known manufacturer defect.