On at our so-called tracks they're usually in the 14.9 range at 90-91. The 5 "mods du jour" are:
(1) cold air intake (make your own (I did) or there are kits are available.)
(2) 160 or 180 t-stat
(3) TR55 plugs at 0.055" gap
(4) Exhaust mods or new system (The GTP has dual mufflers, the GS only a single outlet exhaust)
(5) 3.4" or smaller pulleys (stock is 3.8" on a '97+ sc3800)
Some of the locals north of me have gotten more ambitious and added 1.9 rockers, headers made by a firm called The Other Guys aka TOG, and 3" downpipes w/high flow cats. The sc3800 is my wife's car which I get to drive once every week to 10 days, so I was "spousally limited" to what degree I could add mods. To date my mods include a 3.25" (the wrong size for So Cal 91 octane and no headers, too much KR), an adjustable FPR I bought used off the Web, a custom CAI I fab'd which puts a 9" K&N cone into the DS front wheelwell, custom exhaust consisting of everything aft of the cat (including the "u-bend" by the front exhaust hangar) being cut off and tossed, and straight 3" tubing to the back of the car added which then swedges down to 2.5" near the axle which in turn feeds into the factory muffler (looks factory from the rear), hot-wired fuel pump (a trick from the GN), 160 t-stat, and TR55's. I also modified a factory front strut tower brace and installed it in the trunk, and swapped out the factory swaybars in favor of the fatter swaybars from the 2000 Chevy Impala 9C1 police package.
Regards,
Morgan
'87 GN (11.1s @ 120)
'99 Buick Regal GS (14.22 @ 98.1)
'67 Buick GS California (1 of 544, beautiful original)
'96 Buick Roadmaster Limited LT-1 w/a couple of mods (my stealth Impala SS)