I just did the r34gtt front brake conversion this morning on my m35 axis. As others have said, pretty much direct bolt on. Just had to remove the olive/restrictor from the gtt calipers and the dust shield met Mr hammer which worked well. I managed to get the required clearance without trimming it. The axis rims fit back on without clearance issues which is a bonus. Just got to bleed the brakes after lunch and go for a drive. All in all, very straightforward upgrade.