I did it...you're probably looking at about 20K ballpark figure depending on a lot of things. Here's a list of some of the things you'll need for the conversion:
1. Hydroboost (can get it used if you want) - this requires modifying the end that goes to the pedal - it's at a different angle
2. New steering shaft (available from Flaming River)
3. The motor (duh)
4. The transmission is preferable although lately I've heard that there are some bellhousings out there that mate up to the back of the 4.6 block that will allow you to bolt other Tremecs, etc. to the back instead of using the T56.
- with the transmission you'll need to move (read: re-weld) the trans. mounts to the body
- new driveshaft of the correct length
5. The entire top engine harness complete down to the PCM.
6. Rewire the driver's side of the car to mate up to the PCM harness at the passenger front side.
7. Disable PATS in the 03-04 Cobra with a tune so you can start it
8. Weld up brackets for the intercooler up in front of the car
9. Weld up brackets to mount the intercooler pump
10. The exhaust should bolt up to your muffler pipes, but you'll need new cat pipes/h/x-pipe
11. Modify your cruise control cable to work if you want cruise control
12. You'll need to update to the latest A/C components if you want A/C (and re-wire it)
13. Might need an oil relocation kit to clear the stock steering rack (the stock oil cooler won't clear the lines with the filter on)
14. You'll need a tach adapter to make your stock tachometer work
15. You'll need a speedometer adapter to make your speedometer work with the 6-speed (assuming you use it)
16. K-member for the mod motor mounts (I used an AJE K-member)
I'm sure there's some other things I can't think of at the moment, but that gives you an idea...
bybyz06