My best friend and rival has an 03 Mach 1 with full header back SLP's, x-pipe, ram intake, RP oil, plugs, and rear seat delete kit, and I put about 2 cars on him from 20-120mph in my Z. We've raced several, several times, in all kinds of situations, and it's always been the same outcome. He will admit it to anyone, as annoying as he finds it.
Then again my Z had full exhaust, no cats, raised plenum, and ram air. The howl it made at 6000+ rpms was intense and intimidating. I feared no Mustang, or (no offense) WRX. I took a stage 2 WRX from a 10 mph creep. But that's also with my husky yoko tires that bit hard and a clutch that gripped like no other car I've driven.
'Tis a shame the rest of the car seems so behind. Flawed interior, HORRID transmission, poor LSD, tons of maintenance and recalls, cheap paint, I could go on.