Upgrading from T3 to T34, need some advice
 

My 2wd cossie is running stage 2 on dark greens etc with a bayjoo chip and on a standard T3 turbo. I am upgrading to a T34 with a .63 housing.

Would I need to adjust the fuel mixture or change injectors, or would it be best to get it setup by a professional? If the latter, has anyone had experience with "Engine Advantages" in Whitham?

If the map you're running was written for a T3 turbo, then you will need a new map. The injectors will be fine. Engine Advantages will be fine.

As said chip is written for the engine spec so any(major) change will affect the fuelling EA are ok used them years ago.
tabetha

ok then i will change the turbo and take it straight down to [ea] to get set up. would they do away with my bayjoo chip and write their own chip to suit if so is there any disadvantages in this also is this likely to be expensive, cheers :D

Without having all the details, your spec would seem to be a pretty standard upgrade, so you should be able to get an off-the-shelf chip - phone around various tuners and see what they can do for you.