If you are building a turbo kit don't bother with timing advance. If you advance ignition timing you will have to worry about pinging on very hot days and the extra expense on using higher octane fuel. Not to mention the added load you will put on your pistons for 1hp who knows unless you use a dyno to know your gains. Your best friends will be a Standalone ECU and a tuner whether you go Turbo, Supercharge or Naturally Aspirated because the hp improvement you will get is so much greater than a timing advance.