has anyone out there tried a type r v5 close ratio box with a front diff 3.9 ratio, centre diff ratio 1.1:1 and rear diff 3.54 ratio for a group n rally set up

I suppose I kind of have th closest of what you are talking about.

but the type rs from version 4 onwards had an R180 rear diff, and so a 3.54 rear final drive is not an optin as to my knowledge they dont exist.

I have a different set of ratios in my type r courtesy of lateral performance and these are similar to UK ratios. I also have a 3.9 final drive on my quaife front diff. The transfer case uses 1:1 drop gears and after much sourcng I managed to find a 3.9 final drive for the R180 rear diff. 4.11s are also available but these thinsg are a nightmare to get hold of and aren't cheap.

I had heard the parts are sourced from south africa if that helps! but I know mine came from australia.

You could do it easily by fitting an r160 rear diff, but would then need to change the rear diff casing, the driveshafts and the hubs to the normal impreaz type in the same way as they have done on the P1 which has an r160 rear diff.

THANKS ADAM M .IM RUNNING ALL THOSE RATIOS AT THE MOMENT WITH A R160 REAR HOUSING STI FRONT L/S AND STI REAR L/S JUST FINISHED FITTING THEM ALL SO AM NOT SURE ON OUTCOME BECAUSE I FOUND 4.4 RATIOS WITH TYPE R GEARSET TO BE TOO SHORT ,SO TIME WILL TELL

you will lose out in terms of strength by fitting an r160, but I know of some rally guys running a plated r160 who have never broken one, so you could be fine.

In terms of the final drive, even with my longer ratio gearbox which should make things worse, the car is just fine.

It should be a little better than a standard uk turbo, so I dont think you will have any problem with it.