Originally Posted by Corse-R

Better to not mess with the '4-R' and mixing it with the old MRX4, the new has really different parts (the most noticeable are the bigger rear shock bodies). The 4-R is great as it goes out of the box, needs some parts (front CVD's and if you want, monoblock engine mount and few, very few...).

If you push me, another nice addition to the 4-R are the hard coated 1st gear pinions from Delta (Dave told me that are compatible... 2nd gear ones doesn't have the notch so they go nearer to the 1st gear ones - better to use the stock aluminium ones for the 2nd gear).