SRS is the Safety Restraint System... or airbag. Convertibles are heavier but any Stang can be made fast(er). If you are really wanting to punish it on the streets i'd get a coupe and stiffen everything up. I don't really street race so I like having the option of droppin' the top when the weather is nice. I have no experience with sunroofs on Stangs so I can't help you there.
Brett
------------------
66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
30 Years & 30 inches apart in the driveway!