what kind f header to get for a scion tc?

[EpicRacer]

so ive been reading about different header designs and cant quite determine what would be best for my car. its an 05 tc that is slightly modified, 2.25" exhaust. i dont know if its better to get shorter or longer primary pipes. 4-2-1 or 4-1 system? i dont want to lose the low end torque. even reputable brands make very different headers so im not sure what is best. im not buying it for looks, i want it to actually do something.