Take a look at this to get an idea what different combinations can do:
TurboFord.net Forums: STICKY: Post your Proven Combinations
Everything from stock to 800hp.
Reliability will depend on your combination and how aggressive your tune is. With a tune safe tune, these cars are very reliable with the exception of various boost leaks and the TFI module.
Here is my combo, as posted in the above thread:
Chassis type: 88 mustang hatchback
short block mods/compression ratio/displacement: diamond pistons, crower rods, otherwise stock
head/port work/valve size: home ported, must not be good
cam specs/degrees adv-ret: Ranger roller

intake/throttle body: rounded lower, gutted upper, stock TB
intercooler: small NPR
nitrous system/shot size: 45 shot
exhaust manifold: very early bob log
turbo: stock 60/.63 T3
wastegate: stock
exhaust size: 3" downpipe & cutout, reduced to 2.5 out the back
engine management: Stock LB3
a/f ratio, total timing, boost: 52lb CFI injectors, 12* base timing, 20psi boost
fuel octane/brand/leaded or unleaded: E85
hp@rpm: 306 @ 5700 (mustang dyno)
trq@rpm: none
flex plate/flywheel: C4 pinto
convertor/clutch: stock pinto
transmission: C4
rear/ratio/tire type/tire size: 7.5, 3.73, Nitto 555R
race weight without driver: 2900?
ET/MPH: 12.26 @ 111mph
Without the nitrous, I went 12.96@106 and put 266hp to the wheels (mustang dyno)
next areas to be improved: Next, up to an 85 shot. Also needs engine management BADLY, and a cam.