Well I finally got mine working today and I have to agree with most of what you said. The only thing I don't agree with is the idle screw mod. Mine works fine without doing anything to the idle screw. Idles and starts up just fine.
I kept doing mod after mod to my scoot and could not figure out why it didn't work. Turns out it was the Leo Vince ZX-R exhaust that I bought. I took it off and put the stock exhaust back on an now my scooter takes off. I hit 44mph and I weigh 215 pounds. Here is what I am running
1. Free flow Air filter - Link below but I have to say the one Complex has looks much better
http://www.racingplanetusa.com/filter-power-2850mm-carburetor-connection-white-p-12864-1.html?cPath=2_21356_21380&sessID=5e3045ead88f407841faf40ebe9595d72. I have a 105 main jet in the stock carburetor. I am going to try a 110 to see how that works
3. Malossi 70cc kit
http://www.spi-parts.com/scooter-parts-performance/kymco/kymco-50cc-scooters/kymco-super-8-50cc-2-stoke-air-cooled/70-cc-big-bore-kit-for-kymco-people-50.html4. Polini racing clutch. You don't really need this item. You could simply get some stiffer springs and put them on your stock clutch. I am using the polini green springs. I have them adjusted to the middle since the clutch I am using is adjustable. You'd probably be fine with the stock clutch and springs but your take off may not be quite as good. Overall though top speed should be the same.
I have the malossi variator on mine but I don't think it really does anything. As long as you have the smooth (listed below) I think you will be just fine.
http://www.racingplanetusa.com/drive-face-boss-vario-bushing-naraku-racing-unrestricted-20x38mm-p-336-1.html?cPath=2_21356_21360&sessID=5e3045ead88f407841faf40ebe9595d7I don't know why the Leo Vince ZX-R exhaust does not make the scooter run any better. I even installed a 17.5mm carb and that did not help. The performance was the same as without it which was worse then when the scooter was stock. I am curious how it might help with the stock exhaust but at this point I am happy with the stock carb.
I do also have a longer belt and I got a rear drive pulley that doesn't have a restriction on it but at this point I can't say if those really help. I say this because my performance seems about the same a Complex and he does not have either of these items. I did get to 44 mph so maybe they helped a little but then again it could be the larger main jet. I don't really know. If you want to see what drive pulley and belt and some pictures you can see them here
http://www.kymcoforum.com/index.php?topic=455.msg97422#msg97422 I also tried a Mallosi red torque spring with 9.5 gram and 10.5 gram weights but I found that I liked the stock 8.5 gram weights and the Mallossi white spring better. The white spring seems pretty close to the stock spring so once again you could save some money and avoid that one too.
If anyone has questions I would be happy to answer them for you. I don't want anyone going through what I went through. I will even talk to you on the phone if you want to go over some things.