Hey mate, yep I have had on a silver top in GQ and currently have one in the GQ with TD42T.
Yep its a tight fit but not hard. My slight issue was the wastgate actuator close to the body where the tower brace sits in. Slight little panel beating to allow enough room for engine movement.
Both of mine have been standard exhaust manifold with the T adaptor.
I reckon the high mount would prob be better to be honest as you will be further away from the tower brace area.