if u just want to bolt on a kit and be done w/ it, go for the greddy but be careful that guy has no feedback at all. that means only pay by paypal.
if u are planning to boost more than 7psi and build the motor more, go custom. u will save a lot more $$ in the long run bcoz u will prolly end up upgrading things like the turbo, manifold, wastegate, i/c piping, injectors, etc