I'd say neons, colored radiator hoses, led washers, and a NOS sticker with random Japanese writing that's actually Chinese and has nada to do with cars but you can't tell the difference as long as its' "swooshy".
After that, if you have some dough left, the following are pretty cost-effective per power gain:
a) K&N FIPK and dump-tube hack
b) 1st gen BOV
c) BCS removal (careful!)
followed by:
d) 3" exhaust
e) boost guage
f) JoeP MBC
g) B&M short-throw with Symborski bushing kit (you'll love the shifting with this, makes life easier)
Then, just wait a little for the crankwalk monster, and build a 6-bolt.
