there is no way, they fucked up on something, 99/01 cobras stock put down around 270rwhp, with those bolt ons + tune your likely to get around 300rwhp and maybe about 310rwtq give or take a few. and when your do dyno run its bases from the rear wheels. Now the horsepower looks close enough to be right, but with those boltons you should be seeing your HP line REALLY close to 300 not around the 280 mark or they have no idea how to tune. as for the Torque... even though that would be awesome to have 429rwtq, your showing over a 100+ more that what your really should have. Your showing more torque outputs then boosted 99/01 cobras. Ive seen dynos showing both numbers being a little high or low if it wasnt SAE corrected, but NEVER have a seen on number be about 20hp short and then show torque being 120 higher.
If i were you, id complain to the dyno shop and tell them they fucked up
JLT RAI - MRT O/R HPipe - Borla - 4.10 Gears - 90mm LMAF
SCT Tuner - Eibach ProSport Springs - MM Lower Contol Arms
Baer Drilled & Slotted Rotors w/Hawk Pads - FR500 9"/10.5" w/Nittos
Exedy Mach 400 Clutch - Exedy Flywheel - MGW Shifter