A 28 mph increase from 1/8 to 1/4 is awesome. If you want a little faster ET without running your engine alot harder. Do it in the first 330ft, thats where ET is made. You can put a bigger plantery in and a bigger stall converter. Getting rid of any unnecesary weight, tweeking your carb and your timing. Even going to alcohol would make you 2 tenths faster. I think just tuning what you've got you can get in the 5's relatively easily.