First I found photos of Racer X and lightened them to see the seams
and decorative stitching.
Next I color coded the separate pieces and drew the seams and stitching.
I then drew it on an old shirt to use as size reference.

I made paper patterns using the shirt and then drew
the stitching on them very carefully, referencing the color chart and photos.

Here is a close up of the shoulder piece. The far left is the
photo I used to decide how to draw all of the stitching.