For a 2008 civic coupe what would be the best turbo?

Turbonetics TO4E-50 / Stage 3 .63 A/R?

 

well its more about horsepower than which turbo it is. A mid sized turbo at a decent psi (8 - 10, maybe more if you re-build the engine) would put you at some good numbers, around 200 hp is safe on a daily driver. For more info about turbos, read the stickies at the top of the Nitrous/SC/Turbo section. Alot of questions can be answered there