Would this be remove engine then box, or drop box in place??

Bear in mind this will be done on the floor and not on a ramp, so makes the job a bit harder lol.

I`ve also a set of manifolds to fit, and rocker gaskets to fit so would it be best to remove the engine then the box?

 

If your doin that job mate id take the engine out. Not a big deal to remove the engine and would probably take less time overall rather than trying to do the engine bits while its still in the car. There may be an easier way bud but based on my experience with my last impreza i would do it that way, i did the clutch timing belt and head gaskets at the same time...... Just remember the sealant round the rocker gaskets lol
The biggest struggle i had was getting the box and engine mated together again so would imagine it would be worse the other way round

 

Yeah am leaning that way, but I keep on getting told its better to drop the gearbox alone.

I`ve an engine crane here and engine stand, along with a 2 imperial tonne block and tackle, various axle stands up to a 4ft raise> I`ve removed the engine on an Impreza and refitted it, and found the best way was to leave the release bearing inplace, again against the normal process, just as they go together lift the arm into the bearing and the y go together, then fit the pin and its worked everytime I`ve done it, even on a mates car where they changed the gearbox. But after they dropped the box on his hand sending a stud through his finger slicing his tendon in two lmfao.

But I`d say it was easier to remove the engine, but is there really need and can you change the downpipes and up pipe (if welded together) with the engine in situ or does it HAVE to come out??