I have one. It is plug and play. I did grind out the turbo inlet though to match the manifold. The turbo inlet is oval and smaller than the manifold, presenting a step to the flow.
Other issues... The manifold studs frequently break. It is a good idea to have a spare set in advance. The oil return lower fitting usually needs grinding to fit.
Performance wise, it is not a big difference. Boost comes on a bit earlier, but it is only 2 or 300 rpm. EGTs do drop at the same boost level, so you can increase fueling some. They can put out a lot more boost, so there is more power available if you want to increase boost.