I have a varioplus and a doppler pipe as well as an over ported cylinder. The first thing I did was the carb with the short intake. It ran, Idled and started way better as well as getting maybe 3 mph.
The next thing I did was get the varioplus plate with weights which I have to say was the best upgrade I have for the money, you can just take a ball out variator and get similar results.
Then I got the pipe and unless you are getting a kit it is pretty much a waste of money unless you get a kit.
Lastly I ported the cylinder which is what gave me the most performance gains but I ported the intake too much and now my low end isn't too great but I'm working on that right now.