I use the stock routing and have about 1000 miles since I've done my header install, cheapo duralast wires too, you just need to not be lazy and put them in the plastic looms. The only wire thats gets close to the header is number 6, but theres still about a 1/4 inch of clearance.

BTW, put mine in through the top, had to take valve covers off and do alittle prying, but I think it was alot easier then trying to crawl around and feed them in through bottom(I did the entire install by myself)