As a fairly accurate guide in a 2wd Saff

500bhp will see 180mph
600bhp 190mph
720bhp 200mph
840bhp 206mph
900bhp 210mph
1000bhp maybe 213/214mph

The gearing would have to be spot bollix to achieve these times. Its all very well to say you will pull the Limiter in 5th but is Power falling at that point if so after 170ish you hopes will disapear im afraid. Only 11 Cossies have ever pulled 180 in 1.5miles & hundreds have failed many claiming over 600bhp im afaid. CA Temps after about 30secs on the throttle claim most victims ask people like Porkie. Topspeed runs sound easy, they aint.