Sorry to Hijack the thread, but Ive done a bit of reading on this and apparently all the GT series of Garrett's have restrictors built in.
Now I'm not sure if we should believe this, it seems as though half the people out there say to use restrictors and half the people say they are built in.
I'm about to fit a set of GT2560Rs (707160 - 9, the GT-SS equivalents) to an R32 GTR and I'm in the same boat you were, not sure whether to just bolt them up, or to put restrictors in.
The sticker on the plastic wrap the turbos come in say not to exceed 60psi which leads me to think the restrictors are not built in. Also, in the GT-SS kit (which I didn't get) they have a banjo restrictor to put in place.
Can someone with a bit a bit of knowledge please help clarify this???
I know the turbos will work without the restrictors, but will this put exessive loading on the seals and blow them out 10,000Kms down the line? or are there internal restrictors?