I had the 1 7/8 kooks headers installed along with their full exhaust system. The only fitment issue I had was with one of my over the axle pipes needed trimming down. No clearance issue with the steering shaft. Best two photos I could find.
I have a 03 Cobra heavily modded and a 14 Shelby mildly modded. Honestly I drive my 03 and foxbody twice as much as my Shelby. Now I love them all and hopefully I'll never have to sell any of them. But each one has their own unique characteristics. So like already stated it boils down to...