I've heard of guys here that upgrade to a 3" downpipe and high flow cat. That'* always worth a few more ponies.

I've actually made something like this a few years ago, it does make some difference(anything is better than nothing)
ZZPerformance - HV3 High Velocity Intake Insert #ZZ-HV3NST

all those air intake things do is give you power in the high rpm range and if you never take the car over 3 to 4 thousand rpm you probably never feel it. not worth the money in my opinion. unless its a car you are going to race regularly. and i dont think the trans and other things on that car are going to hold up to regular abuse