Nothing signals the start of summer like the shrieks and screams of thrill-seekers riding the latest pulse-spiking attractions. This year, four Southern California amusement parks deliver $140 million in new diversions designed to terrify or tantalize.
 Pony Express knott's berry farm
Who'll love it: Soccer moms and NASCAR dads
First ride: May 22
The tab: $9 million
Lowdown: Ride astride one of 16 roller-horses on an elongated figure-eight track featuring hairpin manuevers, whoop-de-dos and 60-degree turns.
Fun factor: Launch accelerates from 0 to 38 mph in three seconds.
 Simpsons Ride universal studios
Who'll love it: Fanboys
First ride: May 17
The tab: $40 million
Lowdown: On this motion- simulator ride, visitors join the Springfield clan as the first guests of Krustyland, the cantankerous clown's low-budget theme park complete with the dreaded Tooth Chipper roller coaster.
Fun factor: Visitors enter the attraction through Krusty's mouth, walking along his squishy, unfurled tongue.
 X2 six flags magic mountain
Who'll love it: Adrenaline junkies
First ride: May 24
The tab: $10 million
Lowdown: The oft-troubled X coaster, with rotating 360-degree seats, gets special effects and lighter cars in a much-anticipated rehab.
Fun factor: Military-spec parts and fighter-plane paint promise to make the 75 mph coaster fiercer than X.
 Toy Story Mania Disney's California
Who'll love it: Gamers
First ride: June 17
The tab: $80 million
Lowdown: "Shrunk" to the size of toys, riders sit in carnival trams and travel through a 3-D video game while firing virtual darts, eggs and pies at carnival midway games displayed on giant screens.
Fun factor: Spring-action shooters fire up to six rounds a second.