Today on the highway I twice raced a guy in a pulsar SSS with my top down from 120kph to 180kph.

I started the race assuming that I would walk him as he only appeared to have an aftermarket exhaust. Pulsar SSS = 160hp in a lightish car.

Turnsout that the guy is running a sr20det from a pulsar Gtir 250hp or so.

On both occasions he took me by about 3 car lengths.

How much of a difference would having the top up have made?

 

hehe, Pulsar SSS ... that's funny as they have 140hp. 250hp in a body that's 100kg lighter then the S2000 is going to be pretty quick.

How much of a difference would having the top up have made?

A fair bit at those speeds. To put it in perspective, an S2000 with a roof-up manages ~200kph at the end of Calder straight. With the roof-down in manages ~190kph. Concidering that you enter the straight at ~100kph, that means that roof-up 100-200kph takes the same amount of time is the same as roof-down 100-190kph. That's a decent difference.

 

Oh man! In the states Nissan used to sell a Pulsar NSX. C&D did a report on it an said that they were beat by a grandma to 30 mph and they figured she didn't know they were racing!