You'll have to see what works best for your car, but in mine it was about 3000RPM, drop at the last yellow to give really good reaction times and have fun! I had a slipping clutch problem last fall which has been remedied, so i had slippage in 2nd and 3rd gears like mad! 2nd gear was still slipping at the 1/8 mile mark. I think my best time ended up being 16.8 at 78MPH. Hopefully this fresh clutch will let me be more respectable!
Ford and I both figured out with our mods we need to drop BELOW 3 grand, about 2700.. and don't forget, your TACH will show 3k, but will really be at 3300 or so, so you need to drop a little lower than three k..
I feather it out at 2700, have a nice chirp and be out like a rocket. You need to not just dump the clutch too, feather it, hook and GO.
I dunno about you guys, but my best trip down the strip was a redline dump! Mind you, it was in my 1990 Z24 V6 5spd. I normally would try to just chirp the tires and I ran 16.1's consistently. But then I decided to do a big show burnout in the water box - laid tons of rubber. Then, I staged and when the last light went yellow I popped the clutch! The tires squealed and hooked up instantly - the car pulled WAY harder than ever before and I rocketed to a 15.7! The car ran in the 15.7's consistently until I cracked the block and wound up getting my XD. Go figure!