No freaking idea. How fast can my German Sheperd (ie dog, not an actual german sheperd) run the 100 metres sprint?
If its an old RT the engine could be in any type of condition, they are also a bit like the valvers and have figures all over the place out the box. Odviosly its less than a valver though. You would easily notice 10bhp down on an RT but might not on a valver.
Also what sport exhaust? Is it back box, or does it run from the manifold? Or does it include the manifold? Does it have a cat or not? What air filter do you have? When was it last serviced etc.
All these things can and will make a difference. So to ask that kinda question is impossible.
Paul