I gotta say, firing up a 4.6L Ford v8 after you finish up the twin-screw supercharger installation is pretty otherworldly. What takes it over the top is the first time the loud pedal is mashed out on the road. Did that to my '02 Mustang quite a few years ago now. Don't own the car any longer, but it was a fun run. Lots of 1/4 mile runs, car shows, and it culminated in a magazine feature of the car. Good times.
Now what trips my trigger is diesel engine "rattle" and turbo spooling up (Jetta TDI).
When I was young(er) the bark of my CR250 MX bike was lots of fun too. I actually enjoyed my RM125 more since that was a lot more controllable and much less of a handful in the air. The CR was brutal in every sense.