Whats more important header or exhaust when spraying? I wanna spray, but i still have my stock exhaust system header and exhaust. So what should i replace first?

It would be best if you could do both. Mine as well do it all at once.

I just ordered both. I just bought some cheap 130 dollar header off ebay and a vrs 2.5 exhaust from go fast depot. Can't wait to spray this bad boy!