Seems a little slow...

I too think your doing very well, I don't see why 1.5/8" headers would be too small for a 318, sorry but i disagree on this 100%, this size primary is more then enough for what you have, But there is 1 thing i would change, thats the carb, bigger is not always better, that 318 would run stronger & 60ft. better with a 650dp, & the 60fts. are very weak, it should be in the low 1.8s @ bare minimum, thats a solid 3 tenths right there, your MPH is really good at 102+, thats 13.0s all day long with the right 60ft., theres a good .5 in that car, you just need to find it. my 2 cents!!