Like the above have mentioned, the pass side manifold is the most popular place to put it due to mostly being the easiest place to access.
A BD manifold installed on the drivers side as a low budget upgrade will allow you to mount it in the pre tapped holes.
Another option is to weld a bung in your up pipes, more time consuming, but I prefer that method as you dont have to risk the cast iron manifold cracking with this method.
Any place is good as long as its pre-turbo IMO