Mix together olive oil, garlic, salt and hot pepper flakes; toss with shrimp.
Preheat grill to medium-high; grease grates well. Thread shrimp onto soaked bamboo or metal skewers. Grill shrimp, turning once, for 4 to 5 minutes or until grill-marked, pink and opaque.
In food processor or blender, purée red peppers. Add mayonnaise; blend until smooth.
Spread red pepper mayonnaise over buns; sandwich shrimp and arugula in buns. Serve with lemon wedges.
Tip: To roast red peppers, place peppers on foil-lined baking sheet and broil, turning to char all sides. Place in a plastic bag to steam. Peel off charred skins and remove seeds and stems. Chop and use as desired.