Go with 4.10s for minimum gearing for your cobra. Don't even bother with 3.73s. You might even consider 4.30s depending on how much highway usage and your concern for gas mileage. Alot of cobra owners are going with the 4.30s. I would recommend a minimum of 4.10s.
I wouldn't go more than the 125 shot though you could probably even use a 150 shot but I'm not totally sure on that. NOS is alot of stress on the engine but the DOHC should be able to handle it as long as you have the engine and everything tuned properly (fuel delivery, pressure, etc.).
97 Cobra: I noticed you are from Joplin. I'm in Carthage. Welcome to the board. I noticed you just recently joined. I'm in Joplin alot, especially on weekend nights. We'll have to meet up some time. What does your Cobra look like? Maybe I've seen you around over there. There is only one other stanger from our area on here (that I know of), another buddy of mine from Carthage. Well hope to see ya around.
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FOR SALE: 1996 Mustang GTS: 5-speed, K&N, removed air silencer, 3.73s, 49,000 miles. $11,000.
http://www.mustangworks.com/cgi-bin/moi-display.cgi?388
[This message has been edited by 96GTS (edited 11-02-2000).]
[This message has been edited by 96GTS (edited 11-02-2000).]