the advantage in easy hp/tq is the key here. The 03/04 cobra will take 600rwhp daily and be fine, more will also be attainable (without going into the motor at all) but most say 600-650 is the sweet spot to maintain saftey over time.
The 03/04 cobra stock is actually over 400hp, they dyno about 360/360 stock which is way over the est 390 from the factory. They are just heavy, 3660lbs for coupe and 3780 for vert.... and front end heavy with cast iron block and supercharger weight along with IRS rear end weight.
For a simple pulley swap, intake, exhaust expect 450-470rwhp over the stock 360 when going to a 2.93 pulley vs 3.65 stock supercharger pulley (8psi to 12-14). Most do not require any other mods (other than the tune required) for this, some may need maf or a fuel pump boost.... but thats usually reserved for more than the 2.93 pulley swap.
They suffer from wheel hop, but lower springs (stiffer ones) and such with sticky and bigger tires fix most of this. The bushings are crap for the IRS so swaping to delrin helps a ton here to clean up the slop of the IRS, but the ride is good
The sound of the stock eaton m112 supercharger when you get on it is enough for most, also check my sig for my dyno... they make CRAZY tq down low and all the way across the power band

that = fun.
Finally they are 6 speeds vs 5 speed mach 1's and will hold their value better over time I feel..... and the motors were hand built on the niche line at ford by two builders who stamp the valve cover, not so on the mach or previous cobras.