The majority recommend GRS for the RS Turbo.
I just fitted one the other month and it performs great.

You have to do a bit of jiggling about though.
To fit mine with the Kenlow slimline fan inbetween the cooler and rad i had to move the radiator back using the brackets provided by GRS and make another custom bracket myself. (For the offside end of the rad).
There is a limit to how far back you can locate the radiator without hitting the turbo/actuator. Dont forget the engine moves, especially during hard use so take this into account when relocating the radiator.
I then had to cut a bit out of the top thin bar on the bumper to allow it to fit around the cooler (Which juts out a bit).
You may also then run into problems closing the bonnet properly, as the end tanks on the cooler can hit the underside of the bonnet depending on how far forward it is mounted. A little panel beating on the bonnet framework should overcome this.
I modified my front bumper slightly to increase airflow to the cooler. I didnt remove the main bar though. It looks virtually standard at first glance.
If you have spotlights the brackets will no longer fit, so to retain the lights you have to make custom brackets.

If you want to mount the fan(s) on the front of the cooler, i think you can get away without moving the radiator, and just modding the bumper slightly to allow it to fit around the fans. There will also be no problems closing the bonnet, and the spotlight brackets may just fit.

Hope this helps