have you done a tune up recently? im not trying to be a dumdum (you probably already thought of that) my car (94 vtec model) runs about a 15.42 1/4 mile. i would think that 17.1 is a bit slow and definitley your car should be in the high 15's low 16's. the launch really affects the time. if the car rides fine and has no cel's id think it was the launch. sludge buildup? just throwing ideas out there.

id start with a tune up

hope this helps
--andrew