My advice is, if you want to be really cruel:
Appease all their concerns, tell them it is nothing at all, just a coaster (but with a hint of shifty).
Then, when they get on the ride, just as you leave the station turn and face them and say...
"I'm sorry".
If they say "what for?" - just say.
"I'm sorry". Look very nervous, grip your harness tight, shuffle around uncomfortably and then say something like.
"I don't like this ride really, it's too much, I only go on it to look brave" or something like that.
Then mutter things like "I can't believe I am on this thing again - why do I do it" - etc...
Act really nervous, imagine something that really frightens you, and channel that into your focus as you talk to them - this is THE best time to play on fear and apprehension, and really twist them up. Don't go OTT fake, but keep focus in your mind, your goal is to scare the crap out of them.
"Wow, doesn't that new record breaking coaster look tiny compared to this!" Will also not do any harm.
You lot want to be thankful I didn't design the psychology behind SW7... that's me playing nice
Ultimately the best time to play on the fear and apprehension is when it is naturally heightened by the brain chemicals - that will ultimately heighten the adrenal rush by increasing the fear based hormone epinephrene.
Alternatively, be nice, and let them enjoy it in their own way lol!! Saying nowt about it can be as interesting, so they get to feel and interpret the rides message in their own way.
Should I have posted that lol?
*Thumbs up*