I wantingto go to a big single turbo and do away with twins. What do I need to do and where do i get the parts.

a affordable way is to go with a single ct26 adapter from drift motion it lets you run standard mkiii downpipe too. it looks decent and it is sold as a complete installation kit with lines etc.

a true single turbo manifold is always nicer, just send some emails to a few shops that deal with supra turbo manifolds and dig around on the internet.