I think it depends on the look you are going for. I think both are sweet, but I think the cowl gives it more of an old school muscle feel. I agree with Silver though, 4 is a bit much. It doesn't cut down are your vision much, but it feels like it does. I'd do the 3". Just my opinion.
In the market for a Fox body...
SOLD: 2007 Performance white GT Premium.
Performance: Eibach lowering kit, SVT wheels, Steeda Camber Casters, Steeda short throw, FRPP 4.10's, Airraid CAI, BBK 62mm TB, Brenspeed Detroit Rockers, Pypes Longtubes with O/R H and Violators.
For fun: Window louvers, 15% tint, Raxiom tinted taillights, J&L Audio sub.