I'd pick the Mach because I love that shaker. Plus, it's a slightly newer car...not that it really matters with those two. With a few rear suspension mods you can get it a little smoother. Quality control arms make a big difference with that design. It was very noticeable in my '01 Bullitt. Add a short throw shifter as well and taller rear end and she'll move out. What color is the Mach? Here's a nice spec sheet, just in case. 2003 Ford Mustang Mach 1 Specifications
Someone remind me, wasn't there an issue with the '01 Cobra HP ratings or am I mixing up with the 99-00 years?
2008 Bullitt|Roush M90 w/2.57 pulley & CAI; 90mm MAF; Steeda-UCA, LCAs, Ultralites, links, mounts; MM CC plates; Bilsteins; GT500 FCAs; Brembos; Roush shifter; GT500KR axle back; etc
1969 Coupe Restomod-never complete!
2008 Power Wheels Bullitt Clone
Mustangs from the past: 66 coupe, 69 Coupe, 69 Grande, 2001 Bullitt, 2011 V6
Something to do with the intake manifold. One of the magazines, Motor Trend I think it was, put one on a chassis dyno (after the car not performing as well as they thought it would or should given a 320hp rating) and observed a measurement that didn't jive with the typical or assumed 15% loss between the flywheel and tires. At least that is my limited understanding of how the situation unfolded....
I was going to say Mach because I tend to shy away from convertibles but if the top was well cared for and the car is in good condition everywhere else I would lean towards the Cobra. From what I read the Mach cranks are forged on manual cars but if you are not modding, that is a non-issue. The 15hp difference is also negligible. If you dyno the Mach and want more power out of it, simple intake & exhaust mods and a good tune will close the gap. Factory power ratings should be taken with a grain of salt anyway.
2007 Mustang GT/CS coupe
Procharged--cammed--Lito tuned--coilover suspension