Run a full tank of gas. You have plenty of power so the extra 50-100 lbs isn't a big deal. 1/8th mile is all about the launch and on an S13 with the tank way out back, more weight there should help.
Coilovers (unless they're 4k or less) suck for hooking. Stock rear struts/springs make a great drag setup, and it's only 6 bolts total. Theoretically, jacking up the adjustment (rebound) in the front will transfer load to the rear faster off the line.
No idea why your Gismo won't make proper boost. Check that you didn't accidentally change to a different preset. 17.5psi isn't 320-330whp on a T28. They'll max at 300whp at 16psi, and just add more mid-range torque after that. If you're in the 4-5.5k rpm range during the run, it's probably worth it to run that bit of extra boost to maximize power under the curve.