Dan at MAX USA wrote ...

this is what Eisuke had to say.

He made a jig to perform the work precisely in Japan and he was considering doing it for about $300 for customers however it is a lot of work, and in the USA it may be easier to obtain an S14 subframe and the yanack subframe bushing adaptors which take care of the slight difference in the mounting pattern. Another tip is that some people in Japan claim that you can force the S14 subframe into the factory bushings because they are rubber and the extra tension on the bushing acts like putting on the reinforcement collars. Eisuke cautions that if the bushings are shot this will not work. Another consideration in the s13>to>S14-15 is the diff - the rear cover on your S13 diff will have to be changed to S14 and the front diff mounts will need washers to adapt. In the end the subframe swap accomplishes the same thing - and is less work.