a shop in puchong owner name Kam Sing have some 4-1 ready made but 16v flange, so have to cut the ears and modify.
His 4-1 is 0.7 meters length optimised for around 16,000 rpm, hence I recommend you buy it and modify to 4-2-1 and the secondary should be 0.35 meters - this setup is optimised to 7k rpm.