Variable vanes are cool, I have it on one off my bikes, but the spool up is just as fast on my street bike. You don't get much lag on twins. The main difference is that with the VNT you get a power curve that looks more like a NA engine, with a wastegated turbo (that isn't very big) you get more torque at the middle and less HP at top
An intercooler is always a good idea but it's ugly.. and since I can run 14psi and get 120hp without one I'm happy as it is. The stock engine can't take much more than 120hp and still last for years anyway. If you still want more you can always run on E85, it actually cools the air more than an IC up to about 20psi. I run 28psi on my dragbikes, E85 no IC.
Well, a turbo kit and EFI would cost a little more. But still less than $6,000, even if we include a Wiseco kit and a reprogramming off the ignitor