I did over 50 launches at Meremere on my Type R Gearbox (which would be the same as the RA iirc) 30 of those with anitlag cracking away with zero issues.
I did a 12.7 on low boost (170WKW) which i couldn't repeat on high boost (198wkw) then switched back to low boost and backed it up with another 12.7, go figure. All of my 12s came from racing Version8 (oldies will remember) as i seemed to push harder when racing a mate. Best 60ft of 1.6 on T1Rs on 18in rims. Street tire pressure. Unless your running massive power the 1/4 time is made in the first 2 shifts as sultan said above. The rest is just a cruise really.
Worst thing with the shorter gearbox is hitting limiter in 4th about 50m from the finish line. Change into fifth and it bogs down even iwth a flatchange and anitlag. Peice of shit for drag racing.
The timer starts from when you cross the lights, not when they go green, but in heads up its still the first person to cross the line. Ie a 12s could loose to a 14 if you dick around on the lights. Shallow stage if you can, means your carrying slightly more speed when you do cross the lights.