But you know it isn't all about speed - the Cobra is just a nicer car all around than a stripped heavily modded Civic, relatively speaking, but it's a POS compared to most other cars though, LOL.
Actually a stock Civic is much nicer in terms of build quality, oh, and reliability

Although my Cobra was very reliable for the most part, just had freak things happen to it, not really a result of being poorly made, just shitty work done on it here and there by shops.
Cobra is a blast though, I think it looks great, performs very well for a Mustang, easy to make fast, and a hell of a lot of fun on the street - can't beat the feeling of that instant torque from the Eaton or a KB, and the whine.
You'll like it - just do your research on
http://www.svtperformance.com before you buy, read up on what to check out and read up on the common mods/steps to modding - you probably already know a lot of it though - but it's a great site with excellent information and a lot of helpful people.