People are usually too scared of it just by the idle and the looks (open cockpit, low to ground, flimsy doors, etc...) My driving is usually a factor but I try not to goose it before telling them, "OK that was 1/4 throttle, this is half throttle...You wanna see wide open ??" Very few people ever say, "Sure, floor it..." At almost 3/4 throttle most people are usually either laughing their a$$ off at the thought that something could actually acellerate THAT fast, or looking for something to grab onto and trying to remain calm cause they know it'll all be over in just a few minutes. I usually just cruise with that last group of people, but it's fun to stab it and grab a couple gears just to see that fearful uncomfortableness in their eyes
The best was a friend of mine who loves race cars and knows what 500 + hp in a 2500lb car can do - So he says to me, "Dude, are you sure you know what your doing ??" So at the next stop sign I dump the clutch and do a nice (controlled) 360 in a perfect concentric circle burnout, keep my foot in it and continue on up the street with the rear end hangin' out to the right all the way through second. He never questioned my car control skills again and now asks me to let him know before I goto the skidpad...