I have a CatEye too!
Here are a few things right off the bat, tuning remedies that will help out your bikes performance before you shell out the big bucks...
Make (or buy) a stand; essential for tuning.
Use your stand to: Tune your brakes and chain. When I got my bike the back wheel would barely spin. The rotors (front too) were bent and rubbing on both pads, there was a 14" loop of extra rear brake cable rolled up under the engine and the chain was way too tight.
Just getting the wheels to spin freely will add a little pep into the bike.
Also; Use your stand to tune your carb. Unless your carb is tuned right, you can get EVERY performance part available, and you bike will still putt along, smoke and generally run like cr@p.
I have a stock CatEye, and I can spin the rear tire on it (on DRY ground). It tops out on flats around 30mph and it's not the fastest bike, but hey... I bought an 85lb bike, with the same size engine (essentially) as the mini PB's...
I just get as fast as I can, and ride a lot more comfortably!
Good Luck!
Also, I have a couple of free mods I did, you can check it out:
Free Mods!!!