My son's had a cateye and x1...stock the cat was quicker..After doing the same basic mods on both bikes the x1 would smoke the cat...It all depends on how much money you want to spend and how much work you do to either bike..On the cat the first thing I'd do is get a solid rear hub and eliminate that stupid free wheel, convert the bike to single chain.....Get a piece of semi mudflap and cut a piece to put between the engine mount and frame, this will help with some of the vibration from the engine...I also did this on the x1 after cutting the engine mount off the frame and then bolting it back on with 5/16 bolts and nuts...Also mount the exhaust at the frame with a rubber isolated mount...you don't want any of the engine mounted solid to the frame...
If you get an x1 replace the crappy chain and sprockets with a chain and sprockets from an x2....The x1 chain is basically a bicycle chain, very cheap...The x2 is more like a mini bike chain, much heavier and solid...same chain as the cateye...
If you do upgrades on either bike look on
ebay or on the web for other stores before spending way too much at pbu for the same thing...The pipe I had on my x1 I purchased off
ebay for around $50, same exact thing pbu sells for $145....and yes mine was brand new....