I can only speak for myself, so I will! I LOVE the improvement on my zx/50! 2 1/2 years ago I installed a Malossi bore kit, and ALL the extras that would enhance the kit! Jpres. is CORRECT in saying MOST people are unhappy after their mods. I have found that the main reason is incompatible parts. Just because an OFF BRAND supplier says something will work doesn't mean it will. For example; If you install a full flow air filter, and "performance" exhaust alone, I promise you will melt your piston faster than you can get it to the shop to show off your handy work! All the parts MUST be carefully planed out to work together. Only buy the TOP OF THE LINE PARTS! There is always a risk of a poor install, or incorrect sequencing of installation, but a well planed, and funded modification can produce a well tuned, and most of all reliable machine. The Manufacturer builds a solid well rounded machine designed to require as little maintenance as is possible. You can modify your machine to gain more performance, and you will have to spend alot more time maintaining it. Fortunately scooter are easy on the wallet as far as oil, and MOST spare parts. Some things are just overkill when it comes to big bore kits. Find the most common size, and tune the Hell out of it. I have seen 125cc "stroker" kits for the dio/zx, and I think for a few laps around the circuit they would be the most fun you could have on a "throw away" motor. But you want to ride for a few years...right? Pick a common size jug kit, form a TOP manuf., install your cdi, work on the cvt to get it all to the ground. You will have to re-jet your carb to get the extra fuel, so now is where you can lay low, and let the piston/cyl. break in. You can next add the cam, exhaust, and free flow air filter. (a little more re-jetting) After that it is all cosmetic; race stickers, lighted valve stem caps, whatever... My highest recommendation is to stay away from distributors or local dealers until you have TALKED to the techs. at a company like Malossi, Pollini, NYC ect. Everyone has their own in house recommendation, but if you want power, and reliability TALK to the people that have designed the parts for those purposes. Then you can shop around for the best price on the best parts. You could always PM me for more info on what MY experiences have been, and I will tell you here that taking a 35mph 50cc scooter to a 63mph 70cc scooter has been one of the most fun and least expensive hobbies I have had! Just to finish in the last 2 1/2 years I have replaced only my rollers, belt, clutch springs, and tires, due to wear. I melted one piston due to poor quality 2t oil, and replaced three cdi's. (the cdi I now purchase direct from Suitia w/ NO trouble so far). So I don't want to go against the flow but I believe you can get a LOT more out of your scoot if you do it right the first time! Just MY opinion...